- Sep 1 France creates Greater Lebanon
- Sep 1 New town hall of Rotterdam opens
- Sep 2 W Somerset Maugham's "East of Suez" premieres in London
- Sep 4 Last day of Julian civil calendar (in parts of Bulgaria)
- Sep 4 Man o' War wins the 1 5/8-mile Lawrence Realization Stakes at Belmont Park by 100 lengths, the largest winning margin in modern thoroughbred racing history; world record time 2.40.8
- Sep 5 Iron monument unveiled at Stone churches, Flanders
Boxing Title Fight
Sep 6 Jack Dempsey KOs Billy Miske in 3 for heavyweight boxing title 1st radio broadcast of a prizefight
Jack Dempsey
- Sep 6 US Men's National Tennis Championship, Forest Hills NY: Bill Tilden wins 1st of 6 straight US titles; beats Bill Johnston 6-1, 1-6, 7-5, 5-7, 6-3
- Sep 8 US Air Mail service begins (NYC to San Francisco)
- Sep 12 7th Olympic games close in Antwerp Belgium
- Sep 14 The Trial of Sacco & Vanzetti: Sacco and Vanzetti indicted for murder
- Sep 16 The "Wall Street bombing" occurs at 12:01 when a horse-drawn wagon explodes on Wall Street, New York, killing 38 and injuring 143
- Sep 17 Cards set a record of 12 consecutive hits in 4th (10) & 5th (2) innings
- Sep 17 National Football League is born in Canton, Ohio; 12 teams pay $100 each to join American Professional Football Association; re-named the NFL in 1922
- Sep 20 Foundation of the Spanish Legion.
- Sep 22 Chicago grand jury convenes to investigate charges that 8 White Sox players conspired to fix the 1919 World Series
- Sep 23 Alexander Millerand elected president of France
- Sep 23 Despite Japanese protests, China withdraws recognition of Tsarists representatives in China
- Sep 25 Vern Bradburn of Winnipeg Victorias kicks 9 singles in a game
- Sep 25 34th U.S. Women's National Championship: Molla Bjurstedt Mallory beats Marion Zinderstein (6-3, 6-1)
- Sep 28 8 White Sox indicted, threw 1919 World Series (Black Sox scandal)
- Sep 28 Dirk Fock appointed as governor-general of Dutch East Indies
Baseball Record