The tournament was first held in August 1881 at the Newport Casino, Newport, Rhode Island and in that first year only clubs that were members of the United States National Lawn Tennis Association were permitted to enter. From 1884 through 1911, the tournament used a challenge system whereby the defending champion automatically qualified for the next year's final. In 1915, the tournament had outgrown its venue on Rhode Island and moved to the West Side Tennis Club at Forest Hills, New York. From 1921 through 1923, it was played at the Germantown Cricket Club in Philadelphia and returned to Forest Hills in 1924.
In the first few years of the United States National Championship only men competed and the tournament was known as the US National Singles Championships for Men. Six years after the men's nationals were first held, the first official U.S. Women's National Singles Championship was held at the Philadelphia Cricket Club in 1887, accompanied by the U.S. Women's National Doubles Championship (not held for the next two years) and U.S. Mixed Doubles Championship (not held in 1899). Between 1890 and 1906 sectional tournaments were held in the east and the west of the country to determine the best two teams, which competed in a play-off to see who would play the defending champions in the challenge round.
The open era began in 1968 when all five events were merged into the US Open, held at the West Side Tennis Club in Forest Hills, New York. The 1968 combined tournament was open to professionals for the first time. That year, 96 men and 63 women entered the event, and prize money totaled $100,000 ($668,325 today).
In 1970, the US Open became the first of the Grand Slam tournaments to use a tiebreak at the end of a set. The US Open is also the only Grand Slam that continues to use the tiebreak in a deciding 5th set.
All the other three grand slams play it out with service games in the 5th set. Jimmy Connors is the only individual to have won US Open singles titles on all three surfaces (grass, clay, hardcourt), while Chris Evert is the only woman to win on two surfaces