January
January 1 – In American football, the University of California, Berkeley defeats Ohio State 28–0 in the Rose Bowl.
January 2
The football club Cruzeiro Esporte Clube from Belo Horizonte is founded as Palestra Italia in Brazil.
The first religious radio broadcast is heard over station KDKA AM in Pittsburgh.
The Spanish liner Santa Isabel sinks off Villa Garcia; 244 die.
The De Young Museum opens in Golden Gate Park, San Francisco.
January 20 – The British K-class submarine HMS K5 sinks in the English Channel; all 56 onboard die.
January 21
The Italian Communist Party is founded in Livorno.
Women's suffrage is attained in Sweden.
January 25 – The Italian battleship Leonardo da Vinci is righted in Taranto Harbour.
February
February 12 – Red Army invasion of Georgia: The Democratic Republic of Georgia is invaded by forces of Bolshevist Russia.
February 20 – The Young Communist League of Czechoslovakia is founded.
February 21 – Iranian events of 1921: Rezā Khan and Zia'eddin Tabatabaee stage a coup d'état in Iran.
February 25 – Red Army invasion of Georgia: The Red Army enters the Georgian capital Tbilisi and installs a Moscow-directed communist government.
February 27 – The International Working Union of Socialist Parties is formed in Vienna.
February 28 – The Kronstadt rebellion is initiated by sailors of the Soviet Navy's Baltic Fleet.
March
March 1 – The city of Kiryū, located in Gunma Prefecture, Japan, is founded.
March 4 – Warren G. Harding is inaugurated as the 29th President of the United States.
March 5 – Irish War of Independence: Clonbanin Ambush: Irish Republican Army kills Brigadier General Cumming.
March 6 – The Portuguese Communist Party is founded.
March 8
Spanish Premier Eduardo Dato Iradier is assassinated while exiting the parliament building in Madrid.
Allied forces occupy Düsseldorf, Ruhrort and Duisburg.
March 12 – The İstiklâl Marşı (Independence March), the Turkish National Anthem, is officially adopted.
March 13 – Occupation of Mongolia: The Russian White Army captures Mongolia from China. Roman von Ungern-Sternberg declares himself ruler.
March 14 – Armenian Soghomon Tehlirian assassinates Mehmed Talaat, former Interior Minister of Turkey, in Charlottenburg, Berlin.
March 16 – Six Irish Republican Army men of the Forgotten Ten are hanged in Mountjoy Prison, Dublin.
March 17
The Red Army crushes the Kronstadt rebellion and a number of sailors flee to Finland.
Dr. Marie Stopes opens the first birth control clinic in London, England.
The Second Republic of Poland adopts the March Constitution.
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 Soviet Russia.
Irish War of Independence: Headford Ambush: Irish Republican Army kills at least nine British Army troops.
March 29 – A plebiscite in Silesia votes for re-annexation to Germany.
March 31 – Abkhazia becomes an autonomous republic within the Soviet Union.
April
April – The United States Figure Skating Association is formed.
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 – German–Russian treaty signed in Italy; Soviet Union recognized.
April 20 – Ferenc Molnár's play Liliom is first produced on Broadway in English.
April 27 – The Allies of World War I reparations commission announce that Germany has to pay 132 billion gold marks ($33 trillion) in annual installments of 2.5 billion.
May
May 1–May 7 – Jaffa riots: Riots at Jaffa in Mandatory Palestine result in 47 Jewish and 48 Arab deaths.
May 2–July 5 – Third Silesian Uprising: Poles in Upper Silesia rise against the Germans.
May 3 – The province of Northern Ireland is created within the United Kingdom.
May 5 – Only thirteen spectators attend the football match between Leicester City and Stockport County, the lowest attendance in The Football League's history.
May 14–May 15 – Major geomagnetic storm.
May 14–May 17 – Violent anti-European riots occur in Cairo and Alexandria.
May 16 – The Communist Party of Czechoslovakia is founded.
May 19 – The Emergency Quota Act is passed by the United States Congress, establishing national quotas on immigration.
May 23 – In Leipzig the Leipzig War Crimes Trials start. They will end on July 16.
May 24 – First Northern Ireland general election for the new Parliament of Northern Ireland is held.
May 26 – A general strike begins in Norway.
May 31 – Tulsa race riot begins in Tulsa, Oklahoma. The official death toll is 39, but later investigations suggest the actual toll may be much higher.
June
June 21 – International Hydrographic Bureau (IHB) established as an agency of the League of Nations; continues in this form until April 19, 1946.
June 27 – The first signings of Treaty 11, an agreement between George V, King of Canada, and various Canadian First Nations, are conducted at Fort Providence.
June 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.
June 30 – The death penalty is abolished in Sweden.
July
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
The Irish War of Independence (aka the Anglo-Irish War) comes to a halt after a truce is signed between the belligerents.
The Red Army captures Mongolia from the White Army and establishes the Mongolian People's Republic.
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 Muhammad Ibn 'Abd al-Karim al-Khattabi.
July 22 – The Anglo-Irish truce, agreed 10 days earlier, is officially declared in London.
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 29 – Adolf Hitler becomes Führer of the Nazi Party.
August
August – The United States formally ends World War I.
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 – R38 class airship ZR-2 explodes on her fourth test flight near Kingston upon Hull, England, killing 44 of the 49 Anglo-American crew on board. August 25 – Franklin Roosevelt, 39, is diagnosed with poliomyelitis following a two week illness characterized by paralysis and fevers. He would be permanently disabled after this illness.
August 26
Rising prices cause major riots in Munich.
The assassination of German politician Matthias Erzberger causes the government to declare martial law.
September
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 13 – White Castle hamburger restaurant opens in Wichita, Kansas, the foundation of the world's first fast food chain.
September 21 – The Oppau explosion occurs at BASF's nitrate factory in Oppau, Germany; 500—600 are killed.
October
October 5 – The first broadcast of a World Series game on the radio, by Newark, New Jersey, station WJZ; Pittsburgh station KDKA; and a group of other commercial and amateur stations throughout the eastern United States.
October 8 – The first Sweetest Day is staged in Cleveland, Ohio.
October 10 – Teaching at the University of Szeged starts in Hungary.
October 13 – The Treaty of Kars is signed between the Grand National Assembly of Turkey and the Soviet Socialist Republics of Armenia, Azerbaijan and Georgia, establishing the boundaries between Turkey and the states of the south Caucasus.
October 19 – 'Bloody Night' (Noite Sangrenta): 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.
George Melford's wildly successful silent film The Sheik, which will propel its leading actor Rudolph Valentino to international stardom, is premiered in Los Angeles.
October 24 – The Spanish Army defeats rifkabyl rebels in Morocco.
October 29 – In the United States
Construction of the Link River Dam, a part of the Klamath Project in Oregon, is completed.
Centre College's American football team, led by quarterback Bo McMillin, defeats Harvard University 6–0 to break Harvard's five-year winning streak. For decades afterward, this is called "football's upset of the century."
November
November 4 – After a speech by Adolf Hitler in the Hofbräuhaus in Munich (Germany), members of the Sturmabteilung ("brownshirts") physically assault his opposition.
November 9
The National Fascist Party (Partito Nazionale Fascista or PNF) is founded in Italy.
Albert Einstein is awarded the Nobel Prize in Physics for his work with the photoelectric effect.
Riots in Reykjavík injure most of the small police force.[clarification needed]
November 11 – During an Armistice Day ceremony at Arlington National Cemetery, the Tomb of the Unknown Soldier is dedicated by Warren G. Harding, President of the United States.
November 14 – The Spanish Communist Party is founded.
November 23 - The Sheppard–Towner Act is signed by President Harding, providing federal funding for maternity and child care.
Undated – Hyperinflation rampant in Germany, where 263 marks are now needed to buy a single American dollar, more than 20 times greater than the 12 marks needed in April 1919.
December
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.
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 College is founded by Rabindranath Tagore in Santiniketan, Bengal Presidency, British India.
December 29 – William Lyon Mackenzie King becomes Canada's tenth prime minister.
January 1 – In American football, the University of California, Berkeley defeats Ohio State 28–0 in the Rose Bowl.
January 2
The football club Cruzeiro Esporte Clube from Belo Horizonte is founded as Palestra Italia in Brazil.
The first religious radio broadcast is heard over station KDKA AM in Pittsburgh.
The Spanish liner Santa Isabel sinks off Villa Garcia; 244 die.
The De Young Museum opens in Golden Gate Park, San Francisco.
January 20 – The British K-class submarine HMS K5 sinks in the English Channel; all 56 onboard die.
January 21
The Italian Communist Party is founded in Livorno.
Women's suffrage is attained in Sweden.
January 25 – The Italian battleship Leonardo da Vinci is righted in Taranto Harbour.
February
February 12 – Red Army invasion of Georgia: The Democratic Republic of Georgia is invaded by forces of Bolshevist Russia.
February 20 – The Young Communist League of Czechoslovakia is founded.
February 21 – Iranian events of 1921: Rezā Khan and Zia'eddin Tabatabaee stage a coup d'état in Iran.
February 25 – Red Army invasion of Georgia: The Red Army enters the Georgian capital Tbilisi and installs a Moscow-directed communist government.
February 27 – The International Working Union of Socialist Parties is formed in Vienna.
February 28 – The Kronstadt rebellion is initiated by sailors of the Soviet Navy's Baltic Fleet.
March
March 1 – The city of Kiryū, located in Gunma Prefecture, Japan, is founded.
March 4 – Warren G. Harding is inaugurated as the 29th President of the United States.
March 5 – Irish War of Independence: Clonbanin Ambush: Irish Republican Army kills Brigadier General Cumming.
March 6 – The Portuguese Communist Party is founded.
March 8
Spanish Premier Eduardo Dato Iradier is assassinated while exiting the parliament building in Madrid.
Allied forces occupy Düsseldorf, Ruhrort and Duisburg.
March 12 – The İstiklâl Marşı (Independence March), the Turkish National Anthem, is officially adopted.
March 13 – Occupation of Mongolia: The Russian White Army captures Mongolia from China. Roman von Ungern-Sternberg declares himself ruler.
March 14 – Armenian Soghomon Tehlirian assassinates Mehmed Talaat, former Interior Minister of Turkey, in Charlottenburg, Berlin.
March 16 – Six Irish Republican Army men of the Forgotten Ten are hanged in Mountjoy Prison, Dublin.
March 17
The Red Army crushes the Kronstadt rebellion and a number of sailors flee to Finland.
Dr. Marie Stopes opens the first birth control clinic in London, England.
The Second Republic of Poland adopts the March Constitution.
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 Soviet Russia.
Irish War of Independence: Headford Ambush: Irish Republican Army kills at least nine British Army troops.
March 29 – A plebiscite in Silesia votes for re-annexation to Germany.
March 31 – Abkhazia becomes an autonomous republic within the Soviet Union.
April
April – The United States Figure Skating Association is formed.
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 – German–Russian treaty signed in Italy; Soviet Union recognized.
April 20 – Ferenc Molnár's play Liliom is first produced on Broadway in English.
April 27 – The Allies of World War I reparations commission announce that Germany has to pay 132 billion gold marks ($33 trillion) in annual installments of 2.5 billion.
May
May 1–May 7 – Jaffa riots: Riots at Jaffa in Mandatory Palestine result in 47 Jewish and 48 Arab deaths.
May 2–July 5 – Third Silesian Uprising: Poles in Upper Silesia rise against the Germans.
May 3 – The province of Northern Ireland is created within the United Kingdom.
May 5 – Only thirteen spectators attend the football match between Leicester City and Stockport County, the lowest attendance in The Football League's history.
May 14–May 15 – Major geomagnetic storm.
May 14–May 17 – Violent anti-European riots occur in Cairo and Alexandria.
May 16 – The Communist Party of Czechoslovakia is founded.
May 19 – The Emergency Quota Act is passed by the United States Congress, establishing national quotas on immigration.
May 23 – In Leipzig the Leipzig War Crimes Trials start. They will end on July 16.
May 24 – First Northern Ireland general election for the new Parliament of Northern Ireland is held.
May 26 – A general strike begins in Norway.
May 31 – Tulsa race riot begins in Tulsa, Oklahoma. The official death toll is 39, but later investigations suggest the actual toll may be much higher.
June
June 21 – International Hydrographic Bureau (IHB) established as an agency of the League of Nations; continues in this form until April 19, 1946.
June 27 – The first signings of Treaty 11, an agreement between George V, King of Canada, and various Canadian First Nations, are conducted at Fort Providence.
June 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.
June 30 – The death penalty is abolished in Sweden.
July
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
The Irish War of Independence (aka the Anglo-Irish War) comes to a halt after a truce is signed between the belligerents.
The Red Army captures Mongolia from the White Army and establishes the Mongolian People's Republic.
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 Muhammad Ibn 'Abd al-Karim al-Khattabi.
July 22 – The Anglo-Irish truce, agreed 10 days earlier, is officially declared in London.
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 29 – Adolf Hitler becomes Führer of the Nazi Party.
August
August – The United States formally ends World War I.
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 – R38 class airship ZR-2 explodes on her fourth test flight near Kingston upon Hull, England, killing 44 of the 49 Anglo-American crew on board. August 25 – Franklin Roosevelt, 39, is diagnosed with poliomyelitis following a two week illness characterized by paralysis and fevers. He would be permanently disabled after this illness.
August 26
Rising prices cause major riots in Munich.
The assassination of German politician Matthias Erzberger causes the government to declare martial law.
September
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 13 – White Castle hamburger restaurant opens in Wichita, Kansas, the foundation of the world's first fast food chain.
September 21 – The Oppau explosion occurs at BASF's nitrate factory in Oppau, Germany; 500—600 are killed.
October
October 5 – The first broadcast of a World Series game on the radio, by Newark, New Jersey, station WJZ; Pittsburgh station KDKA; and a group of other commercial and amateur stations throughout the eastern United States.
October 8 – The first Sweetest Day is staged in Cleveland, Ohio.
October 10 – Teaching at the University of Szeged starts in Hungary.
October 13 – The Treaty of Kars is signed between the Grand National Assembly of Turkey and the Soviet Socialist Republics of Armenia, Azerbaijan and Georgia, establishing the boundaries between Turkey and the states of the south Caucasus.
October 19 – 'Bloody Night' (Noite Sangrenta): 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.
George Melford's wildly successful silent film The Sheik, which will propel its leading actor Rudolph Valentino to international stardom, is premiered in Los Angeles.
October 24 – The Spanish Army defeats rifkabyl rebels in Morocco.
October 29 – In the United States
Construction of the Link River Dam, a part of the Klamath Project in Oregon, is completed.
Centre College's American football team, led by quarterback Bo McMillin, defeats Harvard University 6–0 to break Harvard's five-year winning streak. For decades afterward, this is called "football's upset of the century."
November
November 4 – After a speech by Adolf Hitler in the Hofbräuhaus in Munich (Germany), members of the Sturmabteilung ("brownshirts") physically assault his opposition.
November 9
The National Fascist Party (Partito Nazionale Fascista or PNF) is founded in Italy.
Albert Einstein is awarded the Nobel Prize in Physics for his work with the photoelectric effect.
Riots in Reykjavík injure most of the small police force.[clarification needed]
November 11 – During an Armistice Day ceremony at Arlington National Cemetery, the Tomb of the Unknown Soldier is dedicated by Warren G. Harding, President of the United States.
November 14 – The Spanish Communist Party is founded.
November 23 - The Sheppard–Towner Act is signed by President Harding, providing federal funding for maternity and child care.
Undated – Hyperinflation rampant in Germany, where 263 marks are now needed to buy a single American dollar, more than 20 times greater than the 12 marks needed in April 1919.
December
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.
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 College is founded by Rabindranath Tagore in Santiniketan, Bengal Presidency, British India.
December 29 – William Lyon Mackenzie King becomes Canada's tenth prime minister.