The 1940 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, USA. The tournament ran from 2 September until 9 September. It was the 60th staging of the U.S. National Championships and the second Grand Slam tennis event of the year because of the cancellation of Wimbledon and the French Championships due to World War II.
Donald McNeill defeated Bobby Riggs 4–6, 6–8, 6–3, 6–3, 7–5
Alice Marble defeated Helen Jacobs 6–2, 6–3
Jack Kramer / Ted Schroeder defeated Gardnar Mulloy / Henry Prussoff 6–4, 8–6, 9–7 
Sarah Palfrey Cooke / Alice Marble defeated Dorothy Bundy / Marjorie Gladman Van Ryn 6–4, 6–4 
Alice Marble / Bobby Riggs defeated Dorothy Bundy / Jack Kramer 9–7, 6–1 
- ^ Collins, Bud (2010). The Bud Collins History of Tennis (2nd ed.). [New York]: New Chapter Press. pp. 67–68. ISBN 978-0942257700.
- ^ Collins, p. 477
- ^ Collins, p. 480
- ^ Collins, p. 482