| 1920 U.S. National Championships | |
|---|---|
| Date | August 30 – September 6 (M) September 20 – 25 (W) |
| Edition | 40th |
| Category | Grand Slam (ITF) |
| Surface | Grass, outdoors |
| Location | Forest Hills, Queens, NY, U.S. (M) Chestnut Hill, PA, U.S. (W) |
| Venue | West Side Tennis Club (M) Philadelphia Cricket Club (W) |
| Champions | |
| Men's singles | |
 Bill Tilden[1] | |
| Women's singles | |
| Molla Bjurstedt Mallory[1] | |
| Men's doubles | |
| Bill Johnston / Clarence Griffin[2] | |
| Women's doubles | |
Marion Zinderstein /  Eleonora Sears[3] | |
| Mixed doubles | |
| Hazel Wightman / Wallace Johnson[4] | |
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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.