Time in Tennessee, as in all U.S. states, is regulated by the United States Department of Transportation.
About 73 percent of the counties in the state of Tennessee lie in the Central Time Zone, mostly the western and middle grand divisions, while East Tennessee is mostly in the Eastern Time Zone except for three counties in that division.[1][2]
All counties observe Daylight Saving Time.
The IANA time zone database identifier for Tennessee is America/New_York for the Eastern Time Zone portion and America/Chicago for the Central Time Zone portion.[4]