Event of Interest
Sep 1 Frank Wedekind's "Herakles" premieres in Munich

Frank Wedekind
- Sep 2 Communist Party of America organizes in Chicago
- Sep 2 Italy agrees to general voting rights and proportional representation
Treaty of Interest
Sep 3 President Woodrow Wilson set out on a tour of the USA to rouse public opinion behind the Treaty of Versailles and the League of Nations

Woodrow Wilson
- Sep 4 British intervene in Petrograd
Event of Interest
Sep 4 Mustafa Kemal Atatürk, who founded the Republic of Turkey, gathers a congress in Sivas to make decisions as to the future of Anatolia and Thrace.

Mustafa Kemal Atatürk
- Sep 4 US National Championship Men's Tennis, Forest Hills NY: Bill Johnston wins his second US title; beats Bill Tilden 6-4, 6-4, 6-3
- Sep 9 Boston's police force strikes
- Sep 10 Indians Ray Caldwell no-hits Yankees 3-0
Event of Interest
Sep 10 NYC welcomes home General John J. Pershing & 25,000 WW I soldiers

John J. Pershing
Agreement of Interest
Sep 12 Adolf Hitler joins the obscure German Worker's Party as its seventh member, agreeing not with worker's rights, but with its German Nationalism and antisemitism

Adolf Hitler
- Sep 13 Guy Bolton & George Middleton's "Adam & Eve," premieres in NYC
- Sep 14 British regime forbids Sinn Féin Dáil
- Sep 16 American Legion incorporated by an act of US Congress
- Sep 16 Dutch Ruether beats Giants 4-3 to clinch Cincinnati 1st NL pennant
- Sep 18 Dutch second chamber accepts female suffrage
- Sep 18 Hurricane tides 16 feet above normal drowns 280 along Gulf Coast
PGA Championship
Sep 20 PGA Championship Men's Golf, Engineers CC: Defending champion Jim Barnes defeats Fred McLeod, 6 & 5 in the final

Jim Barnes
- Sep 20 Booth Tarkington's "Clarence," premieres in NYC
- Sep 22 -Jan 20] Steel strike in the US
- Sep 24 Boston Red Sox slugger Babe Ruth sets MLB season home run record at 28 off Yankee Bob Shawkey in a 2-1 loss at the Polo Grounds in NYC
- Sep 25 US President Woodrow Wilson suffers a breakdown in Colorado, his health never recovers
- Sep 27 British troops withdraw from the North Russian town of Archangelsk after fighting Bolsheviks/Soviets
- Sep 27 Democratic National Committee votes to allow female members
- Sep 27 Pitcher Bob Shawkey sets then Yank record with 15 strike-outs
- Sep 27 Boston Red Sox slugger Babe Ruth takes his MLB home run record to 29 with a 3rd inning blast in a 7-5 defeat at the Washington Senators' Griffith Stadium
- Sep 28 Fastest major league game (51 mins), Giants beat Phillies 6-1
- Sep 30 Avery Hopwood's "Gold Diggers" premieres in NYC
- Sep 30 Race riot at Elaine, Arkansas