WHAT ALL HAPPENED MAY TO SEPTEMBER 1920
Find out what all happened May to September 1920

In the East Prussian plebiscite the local populace decides to remain with Weimar Germany. (11. July 1920)

Kiev Offensive: Polish troops led by Józef Piłsudski and Edward Rydz-Śmigły and assisted by a symbolic Ukrainian force capture Kiev only to be driven out by the Red Army counter-offensive a month later. (7. May 1920)

The 19th amendment to United States Constitution takes effect, giving women the right to vote. (26. August 1920)

The first commercial radio station, 8MK (now WWJ), begins operations in Detroit, Michigan. (20. August 1920)

Authorities arrest Nicola Sacco and Bartolomeo Vanzetti for alleged robbery and murder. (5. May 1920)

The first game of the Negro National League baseball is played in Indianapolis. (2. May 1920)

During the U.S. Republican National Convention in Chicago, U.S. Republican Party leaders gathered in a room at the Blackstone Hotel to come to a consensus on their candidate for the U.S. presidential election, leading the Associated Press to first coin the political phrase "smoke-filled room". (11. June 1920)

Foundation of the Spanish Legion. (20. September 1920)

Montreal, Quebec radio station XWA broadcasts the first regularly scheduled radio programming in North America. (20. May 1920)

The Nineteenth Amendment to the United States Constitution is ratified, guaranteeing women's suffrage. (18. August 1920)

The Latvian–Soviet Peace Treaty, which relinquished Russia's authority and pretenses to Latvia, is signed, ending the Latvian War of Independence. (11. August 1920)

The congress of the Communist Party of Bukhara opens. The congress would call for armed revolution. (16. August 1920)

Two newly purchased Savoia flying boats crash in the Swiss Alps en route to Finland where they would serve with the Suomen Ilmavoimat, killing both crews. (7. September 1920)

Polish–Soviet War: Battle of Warsaw, which began on August 13, ends with the Red Army's defeat. (25. August 1920)

Ray Chapman of the Cleveland Indians is hit on the head by a fastball thrown by Carl Mays of the New York Yankees, and dies early the next day. Chapman was the second player to die from injuries sustained in a Major League Baseball game, the first being Doc Powers in 1909. (16. August 1920)

Telecommunications: the first transatlantic two-way radio broadcast takes place. (25. July 1920)

The Fountain of Time opens as a tribute to the 100 years of peace between the United States and Great Britain following the Treaty of Ghent. (1. September 1920)

The Art Gallery of Ontario, in Toronto, opens the first exhibition by the Group of Seven. (7. May 1920)

The Wall Street bombing: a bomb in a horse wagon explodes in front of the J. P. Morgan building in New York City – 38 are killed and 400 injured. (16. September 1920)

Polish–Soviet War: The Battle of Radzymin concludes; the Soviet Red Army is forced to turn away from Warsaw. (16. August 1920)