The United States Open Tennis Championships is a hardcourt tennis tournament which is the modern iteration of one of the oldest tennis championships in the world, the U.S. National Championship, for which men's singles was first contested in 1881. Since 1987, the US Open has been chronologically the fourth and final tennis major comprising the Grand Slam each year; the other three are the Australian Open, French Open and Wimbledon. It is held annually in late August and early September over a two-week period. The main tournament consists of five event championships: men's and women's singles, men's and women's doubles, and mixed doubles, with additional tournaments for senior, junior, and wheelchair players. Since 1978, the tournament has been played on acrylic hard courts at the USTA Billie Jean King National Tennis Center at New York City, New York, United States. The US Open is owned and organized by the USTA. Net proceeds from ticket sales are used to promote the development of tennis in the United States as the USTA is a not-for-profit organization.
The US Open has tiebreaks in every set, including the last set. The other three Grand Slam tournaments have tiebreaks in every set other than the last set, and therefore their last set continues indefinitely until a two-game lead is reached.