The 1921 U.S. National Championships was a tennis tournament that took place on the outdoor grass courts at three locations in the United States. The men's singles event was held from September 9 until September 19 at the Germantown Cricket Club in Philadelphia, while the women's singles and doubles events were held from August 15 until August 20 at the West Side Tennis Club in Forest Hills, New York. The men's and mixed doubles competitions took place at Longwood Cricket Club in Chestnut Hill, Massachusetts. It was the 41st staging of the U.S. National Championships and the second Grand Slam tennis event of the year. US Open 1921: September 9–9, 1921 at Germantown Cricket Club (MS) West Side Tennis Club (WS, WD) Longwood Cricket Club (MD, XD). Men's singles: Bill Tilden — 4th major title. Women's singles: Molla Bjurstedt Mallory — 6th major title. Wiki link