His athletic interest began when he was a child. At the age of 12 Smith was playing craps with some friends in an alley when a police officer spotted them and ran after them, attempting to arrest them for illegal gambling. The man caught all of them except Smith. Another day when the officer found Smith, the officer advised him to pursue competitive running.[11]
He competed in the marathon for the United States at the 1912 Summer Olympics. He finished in 17th place.[12] He shared rooms with Jim Thorpe on the way to the Olympics.[9][13] Smith also ran the Boston Marathon 10 years in a row.[14] He finished 10th at the 1912 event with a time of 2:27:46.[15][16] He finished in the top three at the 1913 event.[16][17][18][19][20][21] Smith also participated in at least three Run for the Diamonds events.[22] Harry came in at third place in both 1911 and 1913.[23][24][25] He came first and won in 1912.[26][27] Smith was USA Outdoor Track & Field Champion 10000 m in 1912, a victory he shared with Hannes Kolehmainen.[28][29][30] Later in 1912 Smith won a race called the Union Settlement Road Race and was given a gold medal award, handed to him by congressman Amos Pinchot.[31][32] He won the Coney Island Derby Race in 1913.[33][34]
Smith refrained from competing in the fall of 1914 due to sore feet.[35] While in training Smith had a diet that had him consume little water and instead eat a lot of vegetables.[36] He was of the belief that a marathon runner should never look behind themself, as this throws off one's timing while running. He made an exception to this however when he once encountered Tom Longboat while in a race and exchanged a glance with him. This later became a story he would tell his five daughters.[37] Smith was a member and Captain of the Pastime Athletic Club.[38][39] Supposedly Smith was an early underground sports agent.[40] After his athletic career ended he became a sports columnist for The New York Tribune.[10][41]
He was married to a Greek woman named Elizabeth "Ellie" Poulis.[9][42] Ellie's parents were from the town of Missolonghi, Aetolia-Acarnania. She was born on Ellis Island while her parents were in quarantine and waiting to be granted entry into the United States.[43] Ellie was a dancer and artist in her younger years.[43] Harry and Ellie were the parents of five girls, Helen, Diana, Patricia "Patsy", Elizabeth "Betty" and Joanie.[11][44]
Some time during the 1930s he was the victim of a hit-and-run accident which left him with permanent injury on one of his legs, he was bedridden for a long time and walked with a limp for the rest of his life.[10][45] This left the family in financial troubles. He and his wife helped raise their daughter, Helen Hart's oldest son Smith when she and her husband, Stu, suffered an automobile accident while she was pregnant with their second child, Bruce.[46] His daughter Diana married Jock Osler[47] descendant of Sir William Osler and his daughter Patsy married a man named Jack Forrest, who was the great great grandnephew of Nathan Bedford Forrest.[11]
Note 1: In 1888 both the NAAAA and the AAU held championships
OT: The 1920, 1928, 1932, 1992, 1996, 2000, 2004, 2008, 2012 and 2016 championships incorporated the Olympic Trials, otherwise held as a discrete event.
2020 OT: The 2020 Olympic Trials were delayed and held in 2021 due to the COVID-19 pandemic.
Distance: Until 1924 the event was 5 miles; from 1925–27 and from 1929–31 it was over 6 miles.
* Events before 1906 are considered unofficial. Distances have varied as follows: 2 Miles (1899–1931) and odd numbered years since 2015, 5000 meters (1933–1939), 3 Miles 1932, (1940–1986), and 3000 meters (1987–2014) and even numbered years since 2014