Ballotpedia tracked 22 state legislative battleground chambers in 2018.

Heading into the 2018 elections, Democrats controlled 10 battleground chambers and Republicans controlled 12 battleground chambers.^[1]

Democrats captured six Republican-held battleground chambers in the election—the Colorado State Senate, Maine State Senate, Minnesota House of Representatives, New Hampshire House of Representatives, New Hampshire State Senate, and New York State Senate.

Republicans did not capture any Democratic battleground chambers, but they did enter into a power-sharing agreement in the Alaska House of Representatives, which was previously controlled by Democrats.

Battlegrounds were chambers that we anticipated would be, overall, more competitive than other chambers and have the potential to see significant shifts in party control in the 2018 general elections.

Criteria for identification as a battleground chamber included the majority party's share of seats, the number of competitive races, and more. Read the complete list of criteria here.

The 2018 elections occurred in the aftermath of significant Republican gains in state legislative elections from 2010 to 2016. Eighty-seven of the 99 state legislative chambers in the United States held general elections in 2018. Heading into the 2018 elections, Republicans controlled 32 of the country's 50 state legislatures, Democrats controlled 14, and four legislatures were split between the parties. To learn more about the recent history of state legislative partisan control, click here.

For information on state legislative primary elections, see:

2018 election analysis: Partisan balance of state legislative chambers[edit]

See also: 2018 election analysis: Partisan balance of state legislative chambers

Updated 10:00am EST, December 28, 2018

This content is part of Ballotpedia's analysis of the 2018 midterm elections. For comprehensive election results, click here.

Six state legislative chambers changed partisan control after the 2018 midterm election, all from Republican to Democratic control. Democrats and Republicans ended up splitting control in one Democratic-held chamber—the Alaska House of Representatives.

With the six Democratic pickups (4 senate chambers and 2 house chambers), and the Alaska House split between the parties, Republicans now control a total of 61 state legislative chambers (32 senate, 29 house), and Democrats control 37 (18 senate, 19 house).

Regular elections were held in 87 of the nation's 99 state legislative chambers. Heading into the election, Republicans controlled 67 of 99 legislative chambers—36 senate chambers and 31 house chambers.

The pickups include:

In New Hampshire, both the House and Senate flipped from Republican to Democratic control. This ended the Republican state government trifecta (where one party controls both chambers of the legislature and the governor’s office). Incumbent GOP. Gov. Chris Sununu (R) was re-elected.

In New York, the Senate flipped from Republican to Democratic control. This gave Democrats a trifecta, as they retained control of the House and the Democratic governor, Andrew Cuomo, won reelection. This is one of six trifectas Democrats won in 2018.

Colorado Democrats took control of the Senate, flipping the state from divided power to trifecta control for Democrats.

Maine Democrats won control of the Senate and the governor’s office, assuming trifecta control. Democrats retained control of the state House.

Minnesota replaced one Democratic governor with another, and the House changed from Republican to Democratic control. But the Senate remained in GOP hands.

Historical context:

The Democrats’ flip of six legislative chambers is the most since the Party took control of seven chambers in the 2012 elections. In that year, Democrats flipped two state Senate chambers and five state Houses. Interestingly, four of the chambers which switched control in 2012 were the Minnesota House, New Hampshire House, Maine Senate, and the Colorado Senate.

The six chambers that changed partisan control this year is less than midterm elections in 2010 and 2014. Twenty-two state legislative chambers flipped in 2010 (all but one went from Democrats to Republicans) and nine chambers switched control in 2014 (all went to Republicans).

Overview[edit]

These were the 22 battleground chambers in 2018.

The columns in the chart below list the following information:

Seats up in 2018: This was the number of seats in the chamber that were up for election in 2018.
Margin: This was the difference in seats between the majority and minority parties.
Majority share of seats: This was the percentage of the chamber's total seats controlled by the majority party.
Last time party control changed?: This was the election where the party in power before the 2018 elections took control of the chamber.

2018 battleground chambers
Chamber	Seats up in 2018	Margin	Majority share of seats	Last time party control changed?	Did it flip?
Alaska House of Representatives*	All 40	D+4	55 percent	2016	Power-sharing agreement
Arizona State Senate	17 of 30	R+4	56.7 percent	2002	No
Colorado House of Representatives	All 65	D+7	55.4 percent	2012	No
Colorado State Senate	17 of 35	R+2	51.4 percent	2014	Yes
Connecticut House of Representatives	All 151	D+9	53.0 percent	1986	No
Connecticut State Senate**	All 36	D+0	50 percent	1996	No
Delaware State Senate	10 of 21	D+1	52.4 percent	1974	No
Florida State Senate	22 of 40	R+6	55.0 percent	1994	No
Iowa House of Representatives	All 100	R+17	58.0 percent	2010	No
Maine House of Representatives	All 151	D+3	48.3 percent	2012	No
Maine State Senate	All 35	R+1	51.4 percent	2014	Yes
Minnesota House of Representatives	All 134	R+21	57.5 percent	2014	Yes
Michigan House of Representatives	All 110	R+17	57.3 percent	2010	No
Michigan State Senate	All 38	R+17	71.1 percent	1982^[2]	No
Nevada State Senate	11 of 21	D+2	47.6 percent	2016	No
New Hampshire House of Representatives	All 400	R+45	53.0 percent	2014	Yes
New Hampshire State Senate	All 24	R+4	58.3 percent	2010	Yes
New Mexico House of Representatives	All 70	D+7	54.3 percent	2016	No
New York State Senate*	All 63	R+1	50.8 percent	2010	Yes
Washington House of Representatives	All 98	D+2	51.0 percent	1998	No
Washington State Senate	24 of 49	D+1	51.0 percent	2012	No
Wisconsin State Senate	18 of 33	R+3	54.5 percent	2010	No

*This chamber were controlled by a minority party coalition because some members of the party with the numerical majority caucus with the minority party.
** This chamber was evenly divided 18-18 following the 2016 elections. Democrats maintained an effective majority because Lieutenant Gov. Nancy Wyman (D) could cast tie-breaking votes.

State-by-state breakdown[edit]

This section gives an overview of each of the 22 battleground chambers in 2018 and explains what criteria each chamber met to make our list.

Why were these chambers highlighted?[edit]

Ballotpedia’s approach to determining what was and was not a battleground chamber was both objective and subjective. Our sole objective criterion was if the majority party controlled 55 percent or less of a chamber’s seats heading into an election. For example, heading into the 2018 elections, Republicans in the Colorado Senate controlled 18 out of 35 seats. That’s 51.4 percent, meaning we automatically included the Colorado Senate as a battleground chamber.

Subjective criteria included a range of different considerations:

How many majority party seats were up for election vs. how many minority party seats were up for election?
How many majority party seats did the presidential candidate of the opposite party win in the 2016 presidential election?
In the direction of which party had past state legislative elections trended?
Were there competitive statewide races on the ballot?
Had recent generic ballot surveys favored the minority or majority party in a chamber?
Had control of the chamber recently changed?
How many seats in the chamber were actually competitive based on previous margins of victory?
How many incumbents filed to run for re-election?

Alaska House[edit]

Click [show] to read about the Alaska House.

Partisan control

Although Republicans won a 21-17 majority with two independents in the 2016 elections, the 17 Democrats took effective control of the chamber when they formed a 22-18 coalition with three Republicans and the two independents. The coalition elected Democrat Bryce Edgmon as speaker of the house.

What was at stake?

Republicans needed to gain three seats to take control of the chamber in 2018. They could have also replace the three Republicans who joined the Democratic-coalition in the primary elections on August 21, 2018.

If Republicans had flipped the chamber, retained control of the state Senate, and won the 2018 gubernatorial race, they would have gained a trifecta.

Why was it a battleground?

Competitive seats: In 2016, four seats won by Democrats and one seat won by an independent had a margin of victory that was less than 10 percent. Two Republican seats had a margin of victory less than 10 percent. See the 2018 races to watch here.

Competitive statewide race: Electoral ratings organizations expected the Alaska gubernatorial race to be competitive. The governor's office was held by Bill Walker (I) from 2015 to 2018, a Republican from 2002 to 2014 and a Democrat from 1994 to 2002. Read more about the 2018 gubernatorial race here.

Majority held 55 percent of seats: The Democratic-led coalition controlled 22 of 40 seats, which is 55 percent of the total.

2016 presidential election results: Donald Trump (R) won four districts that elected Democrats to the state House and two districts that elected independents. Hillary Clinton (D) did not win any Republican-controlled districts. See the 2016 presidential results in state legislative districts here.

Recent party control switches: The chamber flipped from Republican to Democratic control in 2016.

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	R	R	R	R	R	D

Arizona Senate[edit]

Click [show] to read about the Arizona Senate.

Partisan control

After the 2016 elections, Republicans held a 17-13 advantage.

What was at stake?

Democrats needed to gain three seats to take control of the chamber in 2018.

If Democrats had flipped the chamber, they would have broken the state's Republican trifecta.

Why was it a battleground?

Competitive seats: In 2016, three Republican seats had a margin of victory that was less than 10 percent. Two Democratic seats had a margin of victory that was less than 10 percent. See the 2018 races to watch here.

2016 presidential election results: Hillary Clinton (D) won a single district that elected a Republican to the state Senate. See the 2016 presidential results in state legislative districts here.

Outside ratings: Governing listed this chamber as "Leans Republican."^[3]

Colorado House[edit]

Click [show] to read about the Colorado House.

Partisan control

Heading into the 2016 elections, Democrats held a 36-29 advantage.

What was at stake?

Republicans needed to gain four seats to take control of the chamber in 2018.

If Republicans had flipped the chamber, retained control of the state Senate, and won the 2018 gubernatorial race, they would have gained a trifecta.

Why was it a battleground?

Competitive seats: In 2016, seven seats won by Democrats had a margin of victory that was less than 10 percent. Two seats won by Republicans had a margin of victory that was less than 10 percent. See the 2018 races to watch here.

Competitive statewide race: Gov. John Hickenlooper (D), who has served as governor since 2010, was term-limited in 2018. Electoral ratings organizations expected the race to succeed Hickenlooper to be competitive between the two parties. The governor's office was previously controlled by a Republican from 1999 to 2006. Read more about the 2018 gubernatorial race here.

Recent party control switches: The chamber flipped from Republican to Democratic control in 2012. It had switched from Democratic to Republican control two years prior in 2010.

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	D	D	R	D	D	D

Colorado Senate[edit]

Click [show] to read about the Colorado Senate.

See also: Colorado State Senate elections, 2018

Partisan control

After the 2016 elections, Republicans held an 18-17 advantage. In December 2017, Sen. Cheri Jahn (D) left the Democratic Party and became an independent, giving Republicans an 18-16 advantage.^[4]

What was at stake?

Democrats needed to gain two seats to take control of the chamber in 2018.

If Democrats had flipped the chamber, retained control of the state Senate, and won the 2018 gubernatorial race, they would have gained a trifecta.

Why was it a battleground?

Competitive seats: These seats were last up in 2014. Two seats won by Republicans had a margin of victory that was less than 10 percent. Five seats won by Democrats had a margin of victory that was less than 10 percent. At least two of the Democratic seats were open because the incumbents were term-limited. See the 2018 races to watch here.

Competitive statewide race: Gov. John Hickenlooper (D), who has served as governor since 2010, was term-limited in 2018. Electoral ratings organizations expected the race to succeed Hickenlooper to be competitive between the two parties. The governor's office was previously controlled by a Republican from 1999 to 2006. Read more about the 2018 gubernatorial race here.

Majority held less than 55 percent of seats: Republicans controlled 18 of 35 seats, which is 51.4 percent of the total.

Partisan balance of seats up for election: 10 of the 17 seats up in 2018 were controlled by Republicans, six were controlled by Democrats, and one was held by an independent.

2016 presidential election results: Hillary Clinton (D) won five districts that elected Republicans to the state Senate, including two districts that were up in 2018. Donald Trump (R) did not win any Democratic-controlled districts. See the 2016 presidential results in state legislative districts here.

Recent party control switches: The chamber switched from Democratic to Republican control in 2014.

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	D	D	D	D	R	R

Connecticut House[edit]

Click [show] to read about the Connecticut House.

Partisan control

After the 2016 elections, Democrats held a 79-72 advantage. Democrats flipped a seat in a February 2018 special election, giving them an 80-71 majority.

What was at stake?

Republicans needed to gain five seats to take control of the chamber in 2018.

If Republicans had flipped the chamber, had taken control of the state Senate, and won the 2018 gubernatorial race, they would have gained a trifecta. Doing just one of those would have broken the state's Democratic trifecta.

Why was it a battleground?

Competitive seats: In 2016, 16 seats won by Democrats had a margin of victory that was less than 10 percent. 12 seats won by Republicans had a margin of victory less than 10 percent. See the 2018 races to watch here.

Competitive statewide race: On April 13, 2017, Gov. Dan Malloy (D) announced that he would not seek a third term.^[5] Electoral ratings organizations expected the race to succeed Malloy to be competitive between the two parties. Heading into the election, two election forecasters rated it "Leans Democratic" and a third rated it as a "Toss-up".^[6] Before Malloy was elected in 2010, the office was controlled by a Republican from 1995 to 2010 and an independent from 1991 to 1995. Read more about the 2018 gubernatorial race here.

Majority held less than 55 percent of seats: Democrats controlled 80 of 151 seats, which is 52.3 percent of the total.

2016 presidential election results: Donald Trump (R) won seven districts that elected Democrats to the state House. Hillary Clinton (D) won 33 districts that elected Republicans to the state House. See the 2016 presidential results in state legislative districts here.

Recent trends: The chamber shifted toward Republicans after the 2010 elections. Democrats fell from a 114-37 advantage prior to 2010 to a 79-72 advantage in 2016, representing a loss of 35 seats.

Connecticut Senate[edit]

Click [show] to read about the Connecticut Senate.

Partisan control

After the 2016 elections, the chamber was evenly split 18-18. Democrats maintained an effective majority because Lieutenant Gov. Nancy Wyman (D) could cast tie-breaking votes.

What was at stake?

Both parties needed to gain one seat to take effective control of the chamber in 2018.

If Republicans had flipped the chamber, had taken control of the state House, and won the 2018 gubernatorial race, they would have gained a trifecta. Doing just one of those would have broken the state's Democratic trifecta.

Why was it a battleground?

Competitive seats: In 2016, two seats won by Democrats and three seats won by Republicans had a margin of victory that was less than 10 percent. Four of those races—three Republican victories and one Democratic victory—had a margin that was 5 percent or less. See the 2018 races to watch here.

Competitive statewide race: On April 13, 2017, Gov. Dan Malloy (D) announced that he would not seek a third term.^[7] Electoral ratings organizations expected the race to succeed Malloy to be competitive between the two parties. Heading into the election, two election forecasters rated it "Leans Democratic" and a third rated it as a "Toss-up."^[6] Before Malloy was elected in 2010, the office was controlled by a Republican from 1995 to 2010 and an independent from 1991 to 1995. Read more about the 2018 gubernatorial race here.

Majority held less than 55 percent of seats: Democrats controlled 18 of 36 seats, which is 50 percent of the total.

2016 presidential election results: Hillary Clinton (D) won nine districts that elected Republicans to the state Senate. Donald Trump (R) did not win any Democratic-controlled districts. See the 2016 presidential results in state legislative districts here.

Recent trends: The chamber shifted toward Republicans after the 2010 elections. Democrats fell from a 23-13 advantage following the 2010 elections to an even tie after the 2016 elections.

Delaware Senate[edit]

Click [show] to read about the Delaware Senate.

Partisan control

After the 2016 elections, Democrats held an 11-10 advantage. After state Sen. Bethany Hall-Long (D) resigned in January 2017 to become lieutenant governor, the chamber was tied 10-10. A special election was held on February 25 to fill Hall-Long's seat. Democrats won the special election and regained an 11-10 advantage.

What was at stake?

Republicans needed to gain one seat to take control of the chamber in 2018.

If Republicans had flipped the chamber, they would have broken the state's Democratic trifecta.

Why was it a battleground?

Competitive seats: The seats were last up for election in 2014. Both parties had one victory that had a margin of less than 10 percent. See the 2018 races to watch here.

Majority held less than 55 percent of seats: Democrats controlled 11 of 21 seats, which is 52.4 percent of the total.

Partisan balance of seats up for election: Five of the 10 seats up in 2018 were controlled by Democrats and five were controlled by Republicans.

Recent trends: The chamber shifted toward Republicans after the 2010 elections. The Democratic majority fell from 15-6 before the 2010 elections to 11-10 following the 2016 elections.

Florida Senate[edit]

Click [show] to read about the Florida Senate.

Partisan control

Republicans had a 25-15 advantage after the 2016 elections. Democrats flipped a seat in a September 2017 special election, bringing the Republican majority to 24-16. State Sen. Jack Latvala (R) resigned in December 2017 and Sen. Dorothy Hukill (R) died in October 2018, which gave Republicans a 22-16 majority with two vacancies.

What was at stake?

Democrats needed to pick up five seats in order to take control of the chamber.

If Democrats had flipped the chamber, they would have broken the state's Republican trifecta.

Why was it a battleground?

Competitive seats: The seats were last up for election in 2016 following a court decision which led to all 40 state Senate seats being up in one election rather than the usual 20. Four Republican seats up in 2018 had margins of victory of less than 10 percent. One Democratic seat up in 2018 had a margin of victory of less than 10 percent in the 2016 election, and another Democratic seat had a margin of victory of less than 10 percent in a 2017 special election. See the 2018 races to watch here.

Partisan balance of seats up for election: Fourteen of the 22 seats up in 2018 were won by Republicans in their last elections.

2016 presidential election results: Hillary Clinton (D) won three districts that elected Republicans to the state Senate, including two districts that were up in 2018. Donald Trump (R) did not win any districts that were won by Democrats in 2016. See the 2016 presidential results in state legislative districts here.

Iowa House[edit]

Click [show] to read about the Iowa House.

Partisan control

Republicans had a 59-41 advantage after the 2016 elections. State Rep. Ken Rizer (R) resigned in June 2018, which gave Republicans a 58-41 majority with one vacancy.

What was at stake?

Democrats needed to pick up 10 seats in order to take control of the chamber.

If Democrats had flipped the chamber, they would have broken the state's Republican trifecta.

Why was it a battleground?

Competitive seats: In 2016, five seats won by Democrats had a margin of victory that was less than 10 percent. Seven seats won by Republicans had a margin of victory that was less than 10 percent. See the 2018 battleground races.

Retirements: Seventeen state House members, 13 Republicans and four Democrats, did not seek re-election in 2018.

Competitive statewide race: Gov. Kim Reynolds (R), who assumed the governorship in 2017 after incumbent Terry Branstad (R) resigned, sought her first elected term in 2018. Electoral ratings organizations expected the race to be competitive between the two parties. The governor's office was previously controlled by a Democrat from 1999 to 2010. Read more about the 2018 gubernatorial race here.

2016 presidential election results: Donald Trump (R) won 10 districts that elected Democrats to the state House. Hillary Clinton (D) won four districts that elected Republicans to the state House.

Recent party control switches: The chamber flipped from Republican to Democratic control in 2006 and then came back under Republican control in 2010.

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	D	D	R	R	R	R

Maine House[edit]

Click [show] to read about the Maine House.

Partisan control

After the 2016 elections, Democrats held a 77-72 majority with two independents. As of October 2018, the Democratic majority was 73-70 with seven independents and one vacancy.

What was at stake?

Republicans needed to gain six seats to take control of more than 50 percent of the chamber's seats in 2018.

If Republicans had flipped the chamber, retained control of the state Senate, and won the 2018 gubernatorial race, they would have gained a trifecta.

Why was it a battleground?

Competitive seats: In 2016, 21 seats won by Democrats had a margin of victory that was less than 10 percent. 17 seats won by Republicans had a margin of victory that was less than 10 percent. Two seats won by independents had a margin of victory that was less than 10 percent. See the 2018 races to watch here.

Competitive statewide race: Gov. Paul LePage (R), who has served as governor since 2010, was term-limited in 2018. Electoral ratings organizations expected the race to succeed LePage to be competitive between the two parties. The governor's office was previously controlled by a Democrat from 2002 to 2010. Read more about the 2018 gubernatorial race here.

Majority held less than 55 percent of seats: Heading into the election, Democrats held 73 of 151 seats, which is 48.3 percent of the total.

2016 presidential election results: Donald Trump (R) won 18 districts that elected Democrats to the state House. Hillary Clinton (D) won eight districts that elected Republicans to the state House. Four of the districts held by independent members in August 2017 went for Clinton and one went for Trump.

Recent party control switches: The chamber flipped from Republican to Democratic control in 2012. It had flipped from Democratic to Republican control two years prior in 2010.

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	D	D	R	D	D	D

Maine Senate[edit]

Click [show] to read about the Maine Senate.

Partisan control

After the 2016 elections, Republicans held an 18-17 majority.

What was at stake?

Democrats needed to gain one seat to take control of the chamber in 2018.

If Democrats had flipped the chamber, retained control of the state House, and won the 2018 gubernatorial race, they would have gained a trifecta.

Why was it a battleground?

Competitive seats: In 2016, five seats won by Democrats had a margin of victory of less than 10 percent. Four seats won by Republicans had a margin of victory of less than 10 percent. See the 2018 races to watch here.

Competitive statewide race: Gov. Paul LePage (R), who has served as governor since 2010, was term-limited in 2018. Electoral ratings organizations expected the race to succeed LePage to be competitive between the two parties. The governor's office was previously controlled by a Democrat from 2002 to 2010. Read more about the 2018 gubernatorial race here.

Majority held less than 55 percent of seats: Republicans controlled 18 of 35 seats, which is 51.4 percent of the total.

2016 presidential election results: Hillary Clinton (D) won five districts that elected Republicans to the state Senate. Donald Trump (R) won four districts that elected Democrats to the state Senate.

Recent party control switches: This chamber flipped party control three times between 2010 and 2014. It flipped from Democratic to Republican control in 2010, back to Democratic control in 2012, and then to Republican control in 2014.

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	D	D	R	D	R	R

Michigan House[edit]

Click [show] to read about the Michigan House.

Partisan control

After the 2016 elections, Republicans held a 63-47 majority. One Democratic seat became vacant and was filled in a special election on November 6, 2018.

What was at stake?

Democrats needed to gain nine seats to take control of the chamber in 2018.

If Democrats had won the chamber, they would have broken the state's Republican trifecta.

Why was it a battleground?

Competitive seats: In 2016, 13 Republican seats had a margin of victory that was less than 10 percent. Six Democratic seats had a margin of victory that was less than 10 percent. See the 2018 races to watch here.

2016 presidential election results: Hillary Clinton (D) won four districts that elected a Republican to the state House. Donald Trump (R) won eight districts that elected a Democrat to the state House. See the 2016 presidential results in state legislative districts here.

Term-limited members: Twenty-four of the chamber's 110 members faced term limits, 13 Democrats and 11 Republicans. Based on the 2016 margin of victory and presidential election results, four term-limited Democrats and four term-limited Republicans were in vulnerable seats.

Outside ratings: Governing listed this chamber as "Leans Republican."^[8]

Recent party control switches: This chamber flipped party control twice between 2006 and 2016. It flipped from Republican to Democratic control in 2006 and back to Republican control in 2010

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	D	D	R	R	R	R

Michigan Senate[edit]

Click [show] to read about the Michigan Senate.

Partisan control

After the 2014 elections, Republicans held a 27-11 majority. One Democratic seat in a safe district became vacant and was filled in a special election on November 6, 2018.

What was at stake?

Democrats needed to gain nine seats to take control of the chamber in 2018.

If Democrats had won the chamber, they would have broken the state's Republican trifecta.

Why was it a battleground?

Term-limited members: Twenty-six of the chamber's 38 members faced term limits, seven Democrats and 19 Republicans. Based on presidential election results from 2012 and 2016, 11 seats held by term-limited Republicans were vulnerable. See the battleground races here.

Minnesota House[edit]

Click [show] to read about the Minnesota House.

Partisan control
After the 2016 elections, Republicans held a 76-57 majority with one vacancy. After a special election was held to fill the vacancy, Republicans gained a 77-57 majority. The Republican majority fell to 76-57 on December 1, 2017, after state Rep. Tony Cornish (R) resigned over sexual harassment allegations. Republicans won the special election to replace Cornish and Democrat Paul Thissen resigned, leaving the Republican majority at 77-56 with one vacancy.

What was at stake?

Democrats needed to gain eleven seats to take control of the chamber in 2018.

If Republicans had retained the chamber and won the 2018 gubernatorial race, they would have gained a trifecta. The Republican-controlled Minnesota State Senate did not hold elections in 2018.

Why was it a battleground?

Competitive seats: In 2016, 12 seats won by Republicans had a margin of victory of less than 10 percent. There was another Republican victory with a margin of less than 10 percent that occurred in a 2017 special election for a seat that did not hold an election in 2016. Nine seats won by Democrats had a margin of victory that was less than 10 percent. See the 2018 races to watch here.

Competitive statewide race: Gov. Mark Dayton (D) was elected as governor in 2010. Electoral ratings organizations expected the 2018 gubernatorial race to be competitive between the two parties. The governor's office was previously controlled by a Republican from 2002 to 2010. Read more about the 2018 gubernatorial race here.

2016 presidential election results: Hillary Clinton (D) won 12 districts that elected Republicans to the state House. Donald Trump (R) won seven districts that elected Democrats to the state House. See the 2016 presidential results in state legislative districts here.

Recent party control switches: This chamber flipped party control three times between 2010 and 2014. It flipped from Democratic to Republican control in 2010, back to Democratic control in 2012, and then to Republican control in 2014.

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	D	D	R	D	R	R

Nevada Senate[edit]

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Partisan control
After the 2016 elections, Democrats held an 11-10 advantage. The Democratic advantage increased to 11-9 after Republican Sen. Patricia Farley switched her partisan affiliation to independent and began caucusing with Democrats. After the resignation of Sen. Mark Manendo (D) in July 2017, the Democratic majority fell to 10-9 with one independent. Republican Becky Harris resigned in January 2018, bringing the Democratic majority to 10-8 with one independent and two vacancies.

What was at stake?

Republicans needed to gain two seats to take control of the chamber in 2018.

Senators elected in 2018 served through 2022 and played a role in the state's redistricting process and a role in referring legislative constitutional amendments to the ballot. In Nevada, both congressional and state legislative district boundaries are drawn by the state legislature. The Nevada legislature can put proposed constitutional amendments on the ballot for voter ratification through a majority vote in both chambers in two consecutive legislative sessions.

If Democrats had retained control of the state Senate and state House and had won the 2018 gubernatorial race, they would have gained a trifecta.

Why was it a battleground?

Competitive seats: Ballotpedia identified three seats that were expected to be competitive in 2018. Two of the districts had close margins of victory in 2014 and one saw its member switch her partisan affiliation from Republican to independent in 2016. See the 2018 races to watch here.

Competitive statewide races: Gov. Brian Sandoval (R), who has served as governor since 2010, was term-limited in 2018. Electoral ratings organizations expected the race to succeed Sandoval to be competitive between the two parties. Heading into the election, Sabato's Crystal Ball had rated it as a "Toss-up."^[9] The governor's office was controlled by a Democrat from 1992 to 1998. Read more about the 2018 gubernatorial race here.

U.S. Senator Dean Heller (R) was expected to have a closely-contested re-election bid, with his race being rated a "Toss-up" by Sabato's Crystal Ball, heading into the election.^[10] Read more about Nevada's 2018 U.S. Senate race here.

Majority held less than 55 percent of seats: Heading into the election, Democrats controlled 10 of 21 seats in the chamber, which is 47.6 percent.

Partisan balance of seats up for election: Four of the 11 seats up in 2018 were controlled by Democrats. Six were controlled by Republicans. One was controlled by an independent.

Recent party control switches: This chamber flipped party control three times between 2008 and 2016. It flipped from Republican to Democratic control in 2008, back to Republican control in 2014, and then to Democratic control in 2016.

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	R	D	D	D	R	D

New Hampshire House[edit]

Click [show] to read about the New Hampshire House.

Partisan control

After the 2016 elections, Republicans held a 227-173 majority. As of October 2018, the Republican majority was 212-167 with two Libertarians and 19 vacancies. The changes were the result of party switching, partisan changes in special elections, and seats becoming vacant. As of 2018, New Hampshire's 400 members are elected from 204 total districts: 105 single-member districts and 99 multi-member districts. The multi-member districts had between two and 11 seats.

What was at stake?

Democrats needed to gain 34 seats to take control of the chamber in 2018.

If Democrats had flipped the chamber, they would have broken the state's Republican trifecta.

Why was it a battleground?

Competitive seats: There were 103 single-member and multi-member districts that could have been competitive in 2018 based on their 2016 results. These 103 districts represent 227 total seats. See the 2018 races to watch here.

Majority held less than 55 percent of seats: As of October 2018, Republicans controlled 212 of 400 seats, which was less than 55 percent.

Recent party control switches: This chamber flipped party control four times between 2006 and 2014. It flipped from Republican to Democratic control in 2006, to Republican control in 2010, to Democratic control in 2012, and then back to Republican control in 2014.

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	D	D	R	D	R	R

New Hampshire Senate[edit]

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Partisan control

After the 2016 elections, Republicans held a 14-10 majority.

What was at stake?

Democrats needed to gain three seats to take control of the chamber in 2018.

If Democrats had flipped the chamber, they would have broken the state's Republican trifecta.

Why was it a battleground?

Competitive seats: In 2016, six Republican seats had a margin of victory that was less than 10 percent. Two Democratic seats had a margin of victory that was less than 10 percent. See the 2018 races to watch here.

2016 presidential election results: Hillary Clinton (D) won two districts that elected Republicans to the state Senate. Another two districts voted for Donald Trump (R) for president and Democrats for state Senate. See the 2016 presidential results in state legislative districts here.

Recent party control switches: The chamber flipped from Democratic to Republican control in 2010.

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	D	D	R	R	R	R

New Mexico House[edit]

Click [show] to read about the New Mexico House.

Partisan control

After the 2016 elections, Democrats held a 38-32 majority in the chamber. After James Smith (R) resigned in 2018, Democrats held a 38-31 majority.

What was at stake?

Republicans needed to gain four seats to take control of the chamber in 2018.

If Democrats had retained the chamber and had won the 2018 governor's race, they would have gained a trifecta.

Why was it a battleground?

Competitive seats: In 2016, five Democratic seats had a margin of victory that was less than 10 percent. Seven Republican seats had a margin of victory of less than 10 percent. See the 2018 races to watch here.

Majority held less than 55 percent of seats: Democrats controlled 38 of 70 seats, which is 54.3 percent of the total.

Recent party control switches: The chamber switched party control in the two elections prior to 2018. In 2014, it switched from Democratic to Republican control and in 2016 it switched back to Democratic control.

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	D	D	D	D	R	D

New York Senate[edit]

Click [show] to read about the New York Senate.

Partisan control

After the 2016 elections, Democrats held a 32-31 numerical majority in the chamber, but a Republican-led majority coalition that included all 31 Republicans, eight Democratic members of the Independent Democratic Conference (IDC), and Democrat Simcha Felder effectively controlled the chamber. Two Democrats resigned on January 1, 2018, to take local positions, leaving the effective majority at 40-21 in favor of Republicans. In April 2018, the eight IDC members rejoined the mainline Democrats and Democrats won both special elections to fill the vacant seats, giving them a 32-31 numerical majority. However, Felder continued his alliance with Republicans, leaving them in control of the chamber.

What was at stake?

Democrats needed to gain one seat to take control of the chamber in 2018.

If Democrats had won the chamber and retained the governor's office and the state Assembly, they would have gained a trifecta.

Why was it a battleground?

Competitive seats: In 2016, five seats won by Republicans had a margin of victory that was less than 10 percent. Two Democratic seats had a margin of victory less than 10 percent. See the 2018 races to watch here.

Majority held less than 55 percent of seats: Heading into the elections, the Republican-led coalition held 32 of 63 seats, 50.8 percent of the total. This included the 31 Republicans elected to the chamber and Democrat Simcha Felder, who caucused with Republicans.

2016 presidential election results: Hillary Clinton (D) won nine districts that elected Republicans to the state Senate. Donald Trump (R) won a single Democratic-controlled district. See the 2016 presidential results in state legislative districts here.

Recent party control switches: The chamber flipped from Democratic to Republican control in 2010 after flipping from Republican to Democratic in 2008 for the first time since 1964.

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	R	D	R	R*	R	R*

*Chamber controlled by Republican-led coalition

Washington House[edit]

Click [show] to read about the Washington House.

Partisan control

After the 2016 elections, Democrats held a 50-48 majority. There are 49 state legislative districts that elect two members each. 23 districts elected two Democrats, 22 districts elected two Republicans, and four districts were split between the parties.

What was at stake?

Republicans needed to gain two seats to take control of the chamber in 2018.

If Republicans had won the chamber, they would have broken Washington's Democratic trifecta.

Why was it a battleground?

Competitive seats: In 2016, four Democratic seats had a margin of victory that was less than 10 percent. Nine Republican seats had a margin of victory that was less than 10 percent. See the 2018 races to watch here.

Majority held less than 55 percent of seats: Heading into the 2018 elections, Democrats controlled 50 seats of 98 seats, which is 51.0 percent of the total.

Washington Senate[edit]

Click [show] to read about the Washington Senate.

Partisan control

Although Democrats won a 25-24 numerical majority the 2016 elections, Republicans maintained effective control of the chamber because Democratic Sen. Tim Sheldon caucused with Republicans. Democrats gained a 26-23 majority in the chamber and control of the chamber after winning a special election on November 7, 2017.

What was at stake?

Republicans needed to gain one seat to take control of the chamber in 2018.

If Republicans had flipped the chamber, they would have broken the state's Democratic trifecta.

Why was it a battleground?

Competitive seats: The seats were last up for election in 2014. One Republican seat had a margin of victory that was less than 10 percent. Two Democratic seats had a margin of victory that was less than 10 percent. See the 2018 races to watch here.

Majority held less than 55 percent of seats: Heading into the 2018 elections, Democrats controlled 26 seats of 49 seats, which is 53.1 percent of the total.

Partisan balance of seats up for election: 10 of the 24 seats up in 2018 were controlled by Republicans and 14 were controlled by Democrats.

2016 presidential election results: Hillary Clinton (D) won six districts that elected Republicans to the state Senate, including four districts that were up in 2018. Donald Trump (R) won two districts that elected Democrats to the state Senate, including one district that was up in 2018. See the 2016 presidential results in state legislative districts here.

Recent party control switches: Democrats gained full control of the chamber after a special election on November 7, 2017. From 2012 to 2016, control of the chamber stayed in Republican hands even though Democrats often had a numerical majority in the chamber. Following the 2012 elections, Republicans took over from Democrats despite the 26-23 Democratic majority. This was because a minority coalition was formed when Democrats Tim Sheldon and Rodney Tom joined all chamber Republicans to form a 25-24 majority. Republicans won outright control of the chamber in the 2014 elections, gaining a 25-24 majority. In 2016, numerical control switched back to Democrats, but Sheldon once again formed a coalition with Republicans to give them effective control of the chamber.

Party control: 2006 - 2017
Election Year:	2006	2008	2010	2012	2014	2016	2017
Winning Party:	D	D	D	R*	R	R*	D

*Chamber controlled by Republican-led coalition

Wisconsin Senate[edit]

Click [show] to read about the Wisconsin Senate.

Partisan control

Republicans won a 20-13 majority in the chamber in the 2016 elections. However, Democrats flipped two seats in 2018 special elections, bringing the Republican majority to 18-15.

What was at stake?

Democrats needed to gain two seats to take control of the chamber in 2018.

If Democrats had flipped the chamber, they would have broken the state's Republican trifecta.

Why was it a battleground?

Competitive seats: In 2014, two Democratic seats had a margin of victory that was less than 10 percent. District 1, which Democrats flipped in a June 2018 special election, also had a margin of victory of less than 10 percent. Two Republicans seats had margins of victory that were just over 10 percent. See the 2018 races to watch here.

Presidential election results: Donald Trump (R) won three districts represented by a Democrat heading into the elections. In one Republican-held seat, Trump won had a 1.0 percent margin of victory. Barack Obama (D) won two other Republican-held seats in the 2012 presidential election. See the 2016 presidential results in state legislative districts here.

Majority holds 55 percent of the seats or less: Republicans held 18 of 33 seats, which was 54.5 percent.

Majority seats up: Ten Republican seats and seven Democratic seats were up in 2018.

Outside ratings: Governing listed this chamber as "Leans Republican."^[11]

Recent party control switches: This chamber flipped party control twice between 2006 and 2016. It flipped from Republican to Democratic control in 2006 and back to Republican control in 2010

Party control: 2006 - 2016
Election Year:	2006	2008	2010	2012	2014	2016
Winning Party:	D	D	R	R	R	R

Outside ratings[edit]

Ballotpedia collected ratings and forecasts of the 2018 state legislative elections from the following organizations:

National Conference of State Legislatures (NCSL)—Authors identified 16 battleground chambers based on a qualitative analysis.
Governing—Author rated chambers as "Safe Democratic/Republican," "Likely Democratic/Republican," "Lean Democratic/Republican," or "Toss-up" based on "interviews with dozens of state and national political sources."
Daily Kos—Author rated chambers as "Safe Democratic/Republican," "Likely Democratic/Republican," "Lean Democratic/Republican," or "Toss-up" based on a qualitative analysis.
Klarner Politics—Author predicted the probability of each party winning a chamber based on a quantitative analysis of past election results and national electoral conditions. Ballotpedia converted the probability scores using this scale: 100%-80%=Safe Democratic/Republican, 79.9%-70%=Likely Democratic/Republican, 69.9-60%=Lean Democratic/Republican, <60%=Toss-up.

Outside ratings and forecasts for state legislative chambers, 2018
Chamber	Pre-election Control	Post-election Control	NCSL	Governing	Daily Kos	Klarner Politics
Alabama House	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Alabama Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Alaska House	D	Power-sharing	Battleground	Toss-up	Lean Democratic	Lean Republican
Alaska Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Arizona House	R	R	Battleground	Likely Republican	Lean Republican	Toss-up
Arizona Senate	R	R	Battleground	Lean Republican	Toss-up	Toss-up
Arkansas House	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Arkansas Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
California Assembly	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
California Senate	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Colorado House	D	D	Safe Democratic	Likely Democratic	Safe Democratic	Safe Democratic
Colorado Senate	R	D	Battleground	Toss-up	Lean Democratic	Likely Democratic
Connecticut House	D	D	Safe Democratic	Lean Democratic	Safe Democratic	Safe Democratic
Connecticut Senate	D	D	Battleground	Toss-up	Toss-up	Likely Democratic
Delaware House	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Delaware Senate	D	D	Safe Democratic	Lean Democratic	Lean Democratic	Likely Democratic
Florida House	R	R	Safe Republican	Likely Republican	Safe Republican	Lean Republican
Florida Senate	R	R	Battleground	Lean Republican	Lean Republican	Likely Republican
Georgia House	R	R	Safe Republican	Likely Republican	Safe Republican	Safe Republican
Georgia Senate	R	R	Safe Republican	Likely Republican	Safe Republican	Safe Republican
Hawaii House	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Hawaii Senate	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Idaho House	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Idaho Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Illinois House	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Illinois Senate	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Indiana House	R	R	Safe Republican	Likely Republican	Safe Republican	Safe Republican
Indiana Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Iowa House	R	R	Safe Republican	Lean Republican	Toss-up	Toss-up
Iowa Senate	R	R	Safe Republican	Likely Republican	Likely Republican	Safe Republican
Kansas House	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Kentucky House	R	R	Safe Republican	Safe Republican	Likely Republican	Likely Republican
Kentucky Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Maine House	D	D	Safe Democratic	Lean Democratic	Likely Democratic	Safe Democratic
Maine Senate	R	D	Battleground	Toss-up	Likely Democratic	Safe Democratic
Maryland House	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Maryland Senate	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Massachusetts House	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Massachusetts Senate	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Michigan House	R	R	Battleground	Lean Republican	Lean Republican	Lean Democratic
Michigan Senate	R	R	Safe Republican	Likely Republican	Likely Republican	Toss-up
Minnesota House	R	D	Battleground	Lean Republican	Toss-up	Toss-up
Missouri House	R	R	Safe Republican	Likely Republican	Safe Republican	Safe Republican
Missouri Senate	R	R	Safe Republican	Likely Republican	Safe Republican	Safe Republican
Montana House	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Montana Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Nevada Assembly	D	D	Safe Democratic	Likely Democratic	Safe Democratic	Safe Democratic
Nevada Senate	D	D	Battleground	Likely Democratic	Likely Democratic	Safe Democratic
New Hampshire House	R	D	Battleground	Lean Democratic	Lean Democratic	Safe Democratic
New Hampshire Senate	R	D	Battleground	Lean Democratic	Lean Republican	Lean Democratic
New Mexico House	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
New York Assembly	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
New York Senate	R	D	Battleground	Lean Democratic	Likely Democratic	Lean Democratic
North Carolina House	R	R	Safe Republican	Likely Republican	Likely Republican	Likely Republican
North Carolina Senate	R	R	Safe Republican	Likely Republican	Safe Republican	Toss-up
North Dakota House	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
North Dakota Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Ohio House	R	R	Safe Republican	Likely Republican	Safe Republican	Safe Republican
Ohio Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Oklahoma House	R	R	Safe Republican	Likely Republican	Safe Republican	Safe Republican
Oklahoma Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Oregon House	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Oregon Senate	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Pennsylvania House	R	R	Safe Republican	Likely Republican	Likely Republican	Likely Republican
Pennsylvania Senate	R	R	Safe Republican	Likely Republican	Safe Republican	Safe Republican
Rhode Island House	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Rhode Island Senate	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
South Carolina House	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
South Dakota House	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
South Dakota Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Tennessee House	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Tennessee Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Texas House	R	R	Safe Republican	Likely Republican	Safe Republican	Safe Republican
Texas Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Utah House	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Utah Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Vermont House	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Vermont Senate	D	D	Safe Democratic	Safe Democratic	Safe Democratic	Safe Democratic
Washington House	D	D	Battleground	Likely Democratic	Safe Democratic	Safe Democratic
Washington Senate	D	D	Battleground	Likely Democratic	Safe Democratic	Safe Democratic
West Virginia House	R	R	Safe Republican	Safe Republican	Safe Republican	Lean Democratic
West Virginia Senate	R	R	Safe Republican	Likely Republican	Likely Republican	Likely Republican
Wisconsin Assembly	R	R	Safe Republican	Likely Republican	Safe Republican	Safe Republican
Wisconsin Senate	R	R	Battleground	Toss-up	Lean Republican	Safe Republican
Wyoming House	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican
Wyoming Senate	R	R	Safe Republican	Safe Republican	Safe Republican	Safe Republican

Partisan balance[edit]

Heading into the 2018 elections, Republicans held a majority of state legislative chambers. As of November 2017, 67 chambers were under GOP control, while Democrats held majorities in 32 chambers.^[12]

The following table details partisan balance in all 99 chambers.

Partisan Control of All 99 State Legislatures
	Pre-election		Post-election
Legislative Chamber					Split
State senates	14	36	18 (+4)	32 (-4)	0
State houses	18	31	19 (+1)	29 (-2)	1
Total:	32	67	37 (+5)	61 (-6)	1

The following table details partisan balance of all 7,383 state legislative seats.

Partisan Balance of All 7,383 State Legislative Seats
	Pre-election			Post-election
Legislative Chamber			^[13]			^[13]
State senates	809	1,135	28	869	1,076	27
State houses	2,314	2,986	111	2,574	2,781	56
Total:	3,123	4,121	139	3,443	3,857	83

Political context[edit]

The 2018 elections occurred in the aftermath of significant Republican gains in state legislative elections from 2010 to 2016. During those years, Republicans increased their control of state legislative chambers, total state legislative seats, and state government trifectas. Together, these gains gave them an advantage over Democrats heading into the 2018 elections.

Changes in chamber partisan control, 2010 to 2017[edit]

See also: Partisan composition of state legislatures

Prior to the 2010 elections, Democrats controlled 61 of the country's 99 state legislative chambers, Republicans controlled 37, and one chamber was split between the parties. In the six years that followed, Republicans made significant gains and took control of many of the chambers that were previously held by Democrats. Following the 2016 elections, Republicans controlled 68 chambers and Democrats controlled 31. After the November 2017 elections, Republicans controlled 67 chambers and Democrats controlled 32.

From 2010 to 2017, there were 54 instances where a state legislative chamber changed partisan control. Of these 54 changes, 40 involved a chamber changing from Democratic to Republican control and 11 involved a chamber changing from Republican to Democratic control. The other three involved chambers that were split between the two parties (Oregon House in 2010 and 2012; Montana House in 2010).

Most of the changes came during major elections but some also came through special elections (Louisiana House in 2010; Washington Senate in 2017) and party switching (Louisiana House in 2010; Mississippi Senate in 2011). In some cases, the party that gained control did not have a numerical majority but instead controlled the chamber through a bipartisan coalition (i.e., Alaska House in 2016). This table does not account for changes in party control or ties in a chamber that lasted for less than one year and were not the result of a regularly scheduled election. An example of this is the brief period of Democratic control in the Virginia State Senate in 2014.^[14]

From 2010 to 2017, 39 chambers switched control: 28 switched control once, seven switched control twice, and four switched control three times. Eleven of the 15 battleground chambers in 2018 switched control at least once from 2010 to 2017. For the 50 instances where a chamber switched control in a regularly scheduled election, the average majority controlled 55.7 percent of its chamber's seat heading into the election.

For this chart, a red box indicates that the chamber flipped from Democratic to Republican control, and a blue box indicates that the chamber flipped from Republican to Democratic control.

Chamber changes in partisan control: 2010-2017
Party changes in 2010	Party changes in 2011	Party changes in 2012	Party changes in 2014	Party changes in 2016	Party changes in 2017
Alabama Senate	Louisiana Senate^[15]^[16]	Alaska Senate	Colorado Senate	Alaska House	Washington Senate
Alabama House	Mississippi Senate^[17]^[18]	Arkansas Senate	Maine Senate	Iowa Senate
Colorado House	Mississippi House	Arkansas House	Minnesota House	Kentucky House
Indiana House	Virginia Senate^[19]	Colorado House	Nevada Senate	Minnesota Senate
Iowa House		Maine Senate	Nevada House	Nevada Senate
Louisiana House^[20]^[21]		Maine House	New Hampshire House	Nevada House
Maine Senate		Minnesota Senate	New Mexico House	New Mexico House
Maine House		Minnesota House	West Virginia Senate
Michigan House		New Hampshire House	West Virginia House
Minnesota Senate		Oregon House^[22]
Minnesota House		Washington Senate
Montana House^[23]
New Hampshire Senate
New Hampshire House
New York Senate
North Carolina Senate
North Carolina House
Ohio House
Oregon House^[24]
Pennsylvania House
Wisconsin Senate
Wisconsin House
Total changes: 22	Total changes: 4	Total changes: 11	Total changes: 9	Total changes: 7	Total changes: 1

State legislative seats from 2010 to 2016[edit]

See also: Changes in state legislative seats during the Obama presidency

Throughout Barack Obama's (D) tenure as president, from 2009 to 2017, Democrats experienced losses in state legislative elections, totaling 968 seats. As of January 2009, Democrats controlled 4,082 of the country's 7,383 legislative seats (55.3 percent). By January 2017, they controlled 3,114 seats (42.2 percent). During the same time, Republicans increased their seats from 3,223 (43.7 percent) to 4,171 (56.5 percent). In 82 of the country's 99 state legislative chambers, Republicans held more seats in January 2017 than they did in January 2009.^[25]

It is normal for a party to lose ground in state legislatures when their party controls the presidency for two terms. Between the time of Franklin Roosevelt (D) and George W. Bush (R), the political party of the president lost, on average, 450 state legislative seats while holding the White House. The losses that the Democratic Party sustained under Obama, however, were exceptional, rivaled only by the terms of Richard Nixon (R) and Dwight Eisenhower (R), when Republicans lost 800 and 843 seats, respectively.

Trifectas from 2010 to 2017[edit]

See also: State government trifectas

A state government trifecta occurs when one political party controls the primary levers of power in a state: the governor's office, the state Senate, and the state House. Since 2010, the Republican Party has increased its number of trifectas and the Democratic Party has seen a decline in its trifectas. Prior to the 2010 elections, Democrats had 17 trifectas, Republicans had 10, and 23 states were under divided government. After the 2016 elections, Republicans had 25 trifectas, Democrats had six, and 19 states were under divided government. In August 2017, Republicans picked up another trifecta when West Virginia Gov. Jim Justice changed his partisan affiliation from Democratic to Republican. In the November 2017 elections, Democrats won a special election in the Washington State Senate and gained control of the chamber. The Democratic Party also took the governorship of New Jersey, although incoming governor Phil Murphy (D) was not sworn in until January 2018. This made Washington and New Jersey Democratic trifectas and brought the total number of trifectas to 26 for Republicans and eight for Democrats, with 16 states under divided government.

This chart shows the number of trifectas each party held heading into elections from 2010 to 2018.

Trifectas by year: 2010-2018
Election	Democratic trifectas	Republican trifectas	States under divided government
Pre-2010 elections	17	10	23
Pre-2012 elections	11	22	17
Pre-2014 elections	12	24	14
Pre-2016 elections	7	23	20
Pre-2018 elections^[26]	8	26	16

Click on the map below to see the trifecta status of different states following elections from 2010 to 2016.

Current state government trifectas

2018 Elections
	Choose a chamber below:
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2018 State; legislative elections
	2019 » « 2016
	2018 elections
	2018 special elections
	Post-election analysis
	State government trifectas
	Number of state legislators by party
	State legislative supermajorities
	Incumbents defeated in state legislative elections
	Partisan balance of state legislative chambers
	State legislative seats flipped
	Races decided by fewer than 100 votes

State government trifectas, post-2025 elections[edit]

State government trifectas, pre-2025 elections[edit]

State government trifectas, post-2024 elections[edit]

State government trifectas, pre-2024 elections[edit]

State government trifectas, post-2022 elections[edit]

State government trifectas, pre-2022 elections[edit]

State government trifectas, post-2020 elections[edit]

State government trifectas, pre-2020 elections[edit]

State government trifectas, post-2018 elections[edit]

State government trifectas, pre-2018 elections[edit]

State government trifectas, post-2016 elections[edit]

State government trifectas, pre-2016 elections[edit]

State government trifectas, pre-2014[edit]

State government trifectas, pre-2012[edit]

State government trifectas, pre-2010[edit]

Learn more about Ballotpedia's analyses of trifectas and state governments

Current state government trifectas

Historical and potential changes in trifectas

Trifectas and legislatively referred constitutional amendments

Who Runs the States Report

Party control of state government

Wave election analysis[edit]

See also: Wave elections (1918-2016)

The term wave election is frequently used to describe an election cycle in which one party makes significant electoral gains. How many seats would Republicans have had to lose for the 2018 midterm election to be considered a wave election?

Ballotpedia examined the results of the 50 election cycles that occurred between 1918 and 2016—spanning from President Woodrow Wilson's (D) second midterm in 1918 to Donald Trump's (R) first presidential election in 2016. We define wave elections as the 20 percent of elections in that period resulting in the greatest seat swings against the president's party.

Applying this definition to state legislative elections, we found that Republicans needed to lose 494 seats for 2018 to qualify as a wave election.

The chart below shows the number of seats the president's party lost in the 10 state legislative waves from 1918 to 2016. Click here to read the full report.

State legislative wave elections
Year	President	Party	Election type	State legislative seats change	Elections analyzed^[27]
1932	Hoover	R	Presidential	-1,022	7,365
1922	Harding	R	First midterm	-907	6,907
1966	Johnson	D	First midterm^[28]	-782	7,561
1938	Roosevelt	D	Second midterm	-769	7,179
1958	Eisenhower	R	Second midterm	-702	7,627
2010	Obama	D	First midterm	-702	7,306
1974	Ford	R	Second midterm^[29]	-695	7,481
1920	Wilson	D	Presidential	-654	6,835
1930	Hoover	R	Presidential	-640	7,361
1954	Eisenhower	R	First midterm	-494	7,513

Footnotes[edit]

↑ Two chambers — the Alaska House of Representatives and the New York State Senate — were controlled by minority coalitions, giving effective control of the chamber to the party with a numerical minority.
↑ Detroit News, "Democrats in Michigan seek to flip state House in 2018," July 8, 2018
↑ Governing, "Democrats Poised to Eat Into GOP's Lead in State Legislatures," May 2, 2018
↑ Denver Post, "Jefferson County state senator ditches Democratic Party," December 30, 2017
↑ Decision Desk HQ, "Governor Malloy (CT) Will Not Seek Third Term," April 13, 2017
↑ ^6.0 ^6.1 Cite error: Invalid <ref> tag; no text was provided for refs named SCB
↑ The Hill, "Connecticut Gov. Malloy not running for reelection," April 13, 2017
↑ Governing, "Democrats Poised to Eat Into GOP's Lead in State Legislatures," May 2, 2018
↑ Sabato's Crystal Ball, "2017-2018 Crystal Ball gubernatorial race ratings," accessed October 18, 2018
↑ Sabato's Crystal Ball, "2018 Crystal Ball Senate race ratings," accessed November 1, 2017
↑ Governing, "Democrats Poised to Eat Into GOP's Lead in State Legislatures," May 2, 2018
↑ Although the Nebraska State Senate elects its members in nonpartisan elections, members of the chamber generally function along party lines when it comes to voting and caucusing. Please see Nebraska State Senate partisan affiliation for more information.
↑ ^13.0 ^13.1 Third party incumbents and vacancies.
↑ The Washington Post, "Virginia Republicans snatched control of the state Senate, ended budget-Medicaid impasse," June 9, 2014
↑ The chamber first changed from Democratic to Republican control in a February 2011 special election. Republicans increased their majority to 24-15 in the 2011 elections.
↑ Fox News, "GOP Candidate Wins Lousiana [sic] Senate Special Election, Shifting Majority," February 20, 2011
↑ The chamber changed partisan control prior to the 2011 elections due to Democrats switching to the Republican Party and special election wins by Republicans. Republicans increased their majority in the 2011 elections to 31-21.
↑ The Washington Post, "Southern Democrats in dire straits; 2011 looms large," January 11, 2011
↑ In the 2011 elections, the chamber changed from a 22-18 Democratic advantage to a 20-20 tie. Republicans effectively controlled the chamber because Lieutenant Gov. Bill Bolling (R) could cast tie-breaking votes.
↑ This chamber did not hold elections in 2010. It switched partisan control in December 2010 when Democrat Noble Ellington changed his party affiliation to Republican. In the regularly-scheduled 2011 elections, Republicans increased their majority to 58-45.
↑ Nola.com, "Louisiana Republicans take first House majority since Reconstruction with latest party switch," December 17, 2010
↑ In this election, the Oregon House changed from a 30-30 tie to a 34-26 Democratic advantage.
↑ This chamber went from a 50-50 tie to a 68-32 Republican advantage in the 2010 elections.
↑ This chamber went from a 36-24 Democratic advantage to a 30-30 tie in the 2010 elections.
↑ Data compiled by Ballotpedia staff
↑ Last updated February 9, 2018.
↑ The number of state legislative seats available for analysis varied, with as many as 7,795 and as few as 6,835.
↑ Lyndon Johnson's (D) first term began in November 1963 after the death of President John F. Kennedy (D), who was first elected in 1960. Before Johnson had his first midterm in 1966, he was re-elected president in 1964.
↑ Gerald Ford's (R) first term began in August 1974 following the resignation of President Richard Nixon (R), who was first elected in 1968 and was re-elected in 1972. Because Ford only served for two full months before facing the electorate, this election is classified as Nixon's second midterm.

[1] Two chambers — the Alaska House of Representatives and the New York State Senate — were controlled by minority coalitions, giving effective control of the chamber to the party with a numerical minority.

[2] Detroit News, "Democrats in Michigan seek to flip state House in 2018," July 8, 2018

[3] Governing, "Democrats Poised to Eat Into GOP's Lead in State Legislatures," May 2, 2018

[4] Denver Post, "Jefferson County state senator ditches Democratic Party," December 30, 2017

[DD-5] Decision Desk HQ, "Governor Malloy (CT) Will Not Seek Third Term," April 13, 2017

[SCB-6] 6.0 ^6.1 Cite error: Invalid <ref> tag; no text was provided for refs named SCB

[7] The Hill, "Connecticut Gov. Malloy not running for reelection," April 13, 2017

[8] Governing, "Democrats Poised to Eat Into GOP's Lead in State Legislatures," May 2, 2018

[SCBG-9] Sabato's Crystal Ball, "2017-2018 Crystal Ball gubernatorial race ratings," accessed October 18, 2018

[SCBS-10] Sabato's Crystal Ball, "2018 Crystal Ball Senate race ratings," accessed November 1, 2017

[11] Governing, "Democrats Poised to Eat Into GOP's Lead in State Legislatures," May 2, 2018

[12] Although the Nebraska State Senate elects its members in nonpartisan elections, members of the chamber generally function along party lines when it comes to voting and caucusing. Please see Nebraska State Senate partisan affiliation for more information.

[third-13] 13.0 ^13.1 Third party incumbents and vacancies.

[14] The Washington Post, "Virginia Republicans snatched control of the state Senate, ended budget-Medicaid impasse," June 9, 2014

[15] The chamber first changed from Democratic to Republican control in a February 2011 special election. Republicans increased their majority to 24-15 in the 2011 elections.

[16] Fox News, "GOP Candidate Wins Lousiana [sic] Senate Special Election, Shifting Majority," February 20, 2011

[17] The chamber changed partisan control prior to the 2011 elections due to Democrats switching to the Republican Party and special election wins by Republicans. Republicans increased their majority in the 2011 elections to 31-21.

[18] The Washington Post, "Southern Democrats in dire straits; 2011 looms large," January 11, 2011

[19] In the 2011 elections, the chamber changed from a 22-18 Democratic advantage to a 20-20 tie. Republicans effectively controlled the chamber because Lieutenant Gov. Bill Bolling (R) could cast tie-breaking votes.

[20] This chamber did not hold elections in 2010. It switched partisan control in December 2010 when Democrat Noble Ellington changed his party affiliation to Republican. In the regularly-scheduled 2011 elections, Republicans increased their majority to 58-45.

[21] Nola.com, "Louisiana Republicans take first House majority since Reconstruction with latest party switch," December 17, 2010

[22] In this election, the Oregon House changed from a 30-30 tie to a 34-26 Democratic advantage.

[23] This chamber went from a 50-50 tie to a 68-32 Republican advantage in the 2010 elections.

[24] This chamber went from a 36-24 Democratic advantage to a 30-30 tie in the 2010 elections.

[25] Data compiled by Ballotpedia staff

[26] Last updated February 9, 2018.

[27] The number of state legislative seats available for analysis varied, with as many as 7,795 and as few as 6,835.

[LBJ-28] Lyndon Johnson's (D) first term began in November 1963 after the death of President John F. Kennedy (D), who was first elected in 1960. Before Johnson had his first midterm in 1966, he was re-elected president in 1964.

[RMN-29] Gerald Ford's (R) first term began in August 1974 following the resignation of President Richard Nixon (R), who was first elected in 1968 and was re-elected in 1972. Because Ford only served for two full months before facing the electorate, this election is classified as Nixon's second midterm.

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2018 State legislative elections
2019 » « 2016

2018 elections
2018 special elections
Post-election analysis
State government trifectas
Number of state legislators by party
State legislative supermajorities
Incumbents defeated in state legislative elections
Partisan balance of state legislative chambers
State legislative seats flipped
Races decided by fewer than 100 votes

State legislative battleground chambers, 2018

2018 election analysis: Partisan balance of state legislative chambers[edit]

Overview[edit]

State-by-state breakdown[edit]

Why were these chambers highlighted?[edit]

Alaska House[edit]

Arizona Senate[edit]

Colorado House[edit]

Colorado Senate[edit]

Connecticut House[edit]

Connecticut Senate[edit]

Delaware Senate[edit]

Florida Senate[edit]

Iowa House[edit]

Maine House[edit]

Maine Senate[edit]

Michigan House[edit]

Michigan Senate[edit]

Minnesota House[edit]

Nevada Senate[edit]

New Hampshire House[edit]

New Hampshire Senate[edit]

New Mexico House[edit]

New York Senate[edit]

Washington House[edit]

Washington Senate[edit]

Wisconsin Senate[edit]

Outside ratings[edit]

Partisan balance[edit]

Political context[edit]

Changes in chamber partisan control, 2010 to 2017[edit]

State legislative seats from 2010 to 2016[edit]

Trifectas from 2010 to 2017[edit]

Current state government trifectas

State government trifectas, post-2025 elections[edit]

State government trifectas, pre-2025 elections[edit]

State government trifectas, post-2024 elections[edit]

State government trifectas, pre-2024 elections[edit]

State government trifectas, post-2022 elections[edit]

State government trifectas, pre-2022 elections[edit]

State government trifectas, post-2020 elections[edit]

State government trifectas, pre-2020 elections[edit]

State government trifectas, post-2018 elections[edit]

State government trifectas, pre-2018 elections[edit]

State government trifectas, post-2016 elections[edit]

State government trifectas, pre-2016 elections[edit]

State government trifectas, pre-2014[edit]

State government trifectas, pre-2012[edit]

State government trifectas, pre-2010[edit]

Wave election analysis[edit]

See also[edit]

Footnotes[edit]