<P> At the 1922 U.S. National Championships the draw for the first time included seeded players in order to avoid leading players drawing against each other in the early rounds . </P> <P> 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 . 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 . In 1970, the US Open became the first Grand Slam tournament to use a tiebreak to decide a set that reached a 6--6 score in games and is the only major to use a tiebreak in the deciding set; the other three grand slams play out the deciding set until a two - game margin is achieved . From 1970 to 1974 the US Open used a best - of - nine point, sudden death tiebreaker before moving to the ITF best - of - twelve point system . In 1973 the US Open became the first Grand Slam tournament to award equal prize money to men and women with that year's singles champions John Newcombe and Margaret Court both receiving $25,000 . Another US Open innovation came in 1975 when floodlights enabled night play for the first time . </P> <P> In 1978 the tournament moved from the West Side Tennis Club, Forest Hills, Queens to the larger USTA National Tennis Center in Flushing Meadows, Queens, three miles to the north . In the process, the tournament switched the court surface from clay, used in the last three years at Forest Hills, to hard courts . 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 (clay, hardcourt). The US Open is the only Grand Slam tournament that has been played every year since its inception . During the 2006 US Open, the complex was renamed the USTA Billie Jean King National Tennis Center in honor of four - time tournament champion and women's tennis pioneer Billie Jean King . </P> <P> From 1984 through 2015, the U.S. Open deviated from traditional scheduling practices for tennis tournaments with a concept that came to be known as "Super Saturday": the men's and women's finals were played on the final Saturday and Sunday of the tournament respectively, and their respective semi-finals were held one day prior . The Women's final was originally held in between the two men's semi-final matches; in 2001, the Women's final was moved to the evening so it could be played on primetime television, citing a major growth in popularity for women's tennis among viewers . This scheduling pattern helped to encourage television viewership, but proved divisive among players because it only gave them less than a day's rest between their semi-finals and championship match . </P>

When did us open switch to hard court