The 1920 U.S. National Championships (now known as the US Open) was a tennis tournament that took place on the outdoor grass courts at the West Side Tennis Club, Forest Hills in New York City and the Philadelphia Cricket Club in Chestnut Hill, Philadelphia. The men's tournament, held in New York City, ran from August 30 until September 6, 1920, while the women's event in Chestnut Hill was held from September 20 through September 25, 1920. It was the 40th staging of the U.S. National Championships and the third Grand Slam tennis event of the year.
See main article: 1920 U.S. National Championships – Men's singles. 
Bill Tilden defeated Bill Johnston 6–1, 1–6, 7–5, 5–7, 6–3 [1]
See main article: 1920 U.S. National Championships – Women's singles. Molla Bjurstedt Mallory defeated Marion Zinderstein 6–3, 6–1[2]
Bill Johnston / Clarence Griffin defeated Roland Roberts / Willis Davis 6–2, 6–2, 6–3
Marion Zinderstein / Eleanor Goss defeated Eleanor Tennant / Helen Baker 13–11, 4–6, 6–3[2]
Hazel Wightman / Wallace Johnson defeated Molla Bjurstedt Mallory / Craig Biddle 6–4, 6–3