1918 1919 1920 - 1921 - 1922 1923 1924
1890s 1900s 1910s - 1920s - 1930s 1940s 1950s
- January 2
- The DeYoung Museum opens in Golden Gate Park, San Francisco.
- January 20 – The Royal Navy K-boat K5 sinks in the English Channel with all 56 hands on board.
- January 21
- February 6 – The Democratic Republic of Georgia is occupied by Bolshevist Russia during the Red Army invasion of Georgia.
- February 25 - the Red Army entered Georgian capital Tbilisi and installed a Moscow directed communist government.
- February 27 – The International Working Union of Socialist Parties is formed in Vienna.
- February 28 – Russian sailors rebel in Kronstadt
- March 1 – The city Kiryu, located in Gunma, Japan, is founded.
- March 4 – Warren G. Harding is inaugurated as the 29th President of the United States.
- March 6 – The Portuguese Communist Party is founded.
- March 8
- March 12 – The İstiklâl Marşı (Independence March) the Turkish National Anthem, officially adopted.
- March 13 – The Russian White Army captures Mongolia from China. Roman Ungern von Sternberg declares himself ruler.
- March 17
- March 18 – The second Peace of Riga ends the Polish-Soviet War. A permanent border is established between the Polish and Soviet states.
- March 21 – New Economic Policy starts in the Soviet Russia.
- March 23 – A plebiscite in Silesia votes for re-annexation to Germany.
- April – The Allies of World War I reparations commission announce that Germany has to pay 132 billion gold marks ($33 billion) in annual installments of 2.5 billion gold marks.
- April 11 – The Emirate of Transjordan is created, with Abdullah I as emir.
- April 14 – In Britain, labour unions for mining, railway and transportation workers call for a strike; the government threatens to call in the army.
- April 16 – The Communist Party of Czechoslovakia is founded.
- April 20 – Ferenc Molnár's play Liliom is first produced on Broadway in English. A flop in its native Hungary when first presented there in 1909, the American production is critically acclaimed and becomes a modern classic, filmed more than once, and eclipsed only when Rodgers and Hammerstein adapt it in 1945 into a hit musical, Carousel, which becomes a stage classic in its own right.
- May 1-May 7 – The riots at Jaffa (Mandatory Palestine) result in 47 Jewish and 48 Arab deaths.
- May 2-July 5 – Third Silesian Uprising: The Poles in Upper Silesia rise against the Germans.
- May 5 – Only 13 spectators attend the soccer match between Leicester City and Stockport County, the lowest attendance in The Football League's history.
- May 6 – A general strike begins in Norway.
- May 8 – The death penalty is abolished in Sweden.
- May 14 – May 17 – Violent anti-European riots occur in Cairo and Alexandria.
- May 14 – May 15 – Major geomagnetic storm.
- May 19 – The Emergency Quota Act passes the U.S. Congress, establishing national quotas on immigration.
- May 24 – Elections are held for the first time for the new Northern Ireland Parliament.
- May 31 – Tulsa Race Riot: The official death toll is 39, but recent investigations suggest the actual toll may be much higher.
- July 1
- The Communist Party of China is officially founded.
- A coal strike ends in England.
- July 2 – U.S. President Warren Harding signs a joint congressional resolution declaring an end to America's state of war with Germany, Austria and Hungary.
- July 4 – A new conservative government is formed in Italy by Ivanoe Bonomi.
- July 11
- July 14 – A Massachusetts jury finds Nicola Sacco and Bartolomeo Vanzetti guilty of first degree murder following a widely-publicized trial.
- July 17 – The Republic of Mirdita is proclaimed near the Albanian-Serbian border with Yugoslav support.
- July 18 – The first BCG vaccination against tuberculosis is given.
- July 21 – Rif War – Battle of Annual: Spanish troops are dealt a crushing defeat at the hands of Abd el-Krim.
- July 22 – The Irish Truce is declared in Britain.
- July 26 – U.S. President Warren G. Harding receives Princess Fatima of Afghanistan and Stanley Clifford Weyman.
- July 27 – Researchers at the University of Toronto led by biochemist Frederick Banting announce the discovery of the hormone insulin.
- July 28 – The Constitutional Assembly of the Kingdom of Serbs, Croats and Slovenes passes the Vidovdan Constitution, despite a boycott of the vote by the communists, and Croat and Slovene parties.
- July 29 – Adolf Hitler becomes Führer of the National Socialist German Workers Party.
- August – The United States formally ends World War I, declaring a peace with Germany.
- August 5 – The first radio baseball game is broadcast; Harold Arlin announces the Pirates-Phillies game from Forbes Field over Westinghouse KDKA, in Pittsburgh.
- August 11 – The temperature reaches 39 degrees Celsius in Breslau; the heat wave continues elsewhere in Europe as well.
- August 23 – King Faisal I of Iraq is crowned in Baghdad.
- August 24 – Airship ZR 2 explodes during a test flight near Hull, England; 41 are killed.
- August 26
- Rising prices cause major riots in Munich.
- The assassination of German politician Matthias Erzberger causes the government to declare martial law.
- September 1 – Poplar Strike in London: Nine members of the Poplar borough council are arrested.
- September 7 – In Atlantic City, New Jersey, the first Miss America Pageant is held.
- September 8 – Sixteen-year-old Margaret Gorman wins the Atlantic City Pageant's Golden Mermaid trophy; pageant officials later dub her the first Miss America.
- September 12 – The Lotta Svärd women's paramilitary auxiliary is founded in Finland.
- September 21 – The Oppau explosion occurs at BASF's nitrate factory in Oppau, Germany; 500—600 are killed.
- October 8 – The first Sweetest Day is staged in Cleveland, Ohio.
- October 10 – Teaching at the University of Szeged starts in Hungary.
- October 19 – A massacre in Lisbon claims the lives of Portuguese Prime Minister António Granjo and other politicians.
- October 21 – A peace conference between Ireland and the United Kingdom begins in London.
- October 24 – The Spanish Army defeats the rifkabyls.
- October 29
- Construction of the Link River Dam, a part of the Klamath Reclamation Project, is completed.
- Centre College's football team, led by quarterback Bo McMillin, defeats Harvard University 6-0 to snap Harvard's five-year winning streak. For decades afterward, this is called "football's upset of the century."
- November 9
- November 11 – During an Armistice Day ceremony at Arlington National Cemetery, the Tomb of the Unknowns is dedicated by U.S. President Warren G. Harding.
- November 14 – The Spanish Communist Party is founded.
- November 7 – The Partito Nazionale Fascista (PNF), National Fascist Party, comes into existence in Italy.
- December 1 – Rising prices cause riots in Vienna.
- December 6 – The Anglo-Irish Treaty establishing the Irish Free State, an independent nation incorporating 26 of Ireland's 32 counties, is signed in London. See Ireland/History.
- Agnes Macphail becomes the first woman to be elected to the Canadian Parliament.
- December 13 – In the Four Power Treaty on Insular Possessions, Japan, the United States, United Kingdom, and France agree to recognize the status quo in the Pacific.
- December 23 – Visva-Bharati University is inaugurated in India.
- December 29 – William Lyon Mackenzie King becomes Canada's tenth prime minister.
- July 31 - Peter Benenson, British founder of Amnesty International (d. 2005)
- 24 December - Remi Schrijnen, Belgian volunteer of the Waffen-SS (d. 2006)