For more details see Twilight of a New Era (1914-1964).
- VII Olympic Games in Paris (France)
- I Winter Olympic Games in Chamonix (France)
- Establishment of the Pan-American Union
- US Congress approves the Commonwealths and Americas Relations Act.
- 1. Workers' Olympiad in Frankfurt am Main (Germany)
- Battle of Mecca (Confederation of Arab States)
- Occupation of Riyadh (Confederation of Arab States)
- March Republican Herbert Hoover is inaugurated as the 30th President of the United States.
- 26 June – Santa Barbara Earthquake of 1925: A 6.3 earthquake destroys downtown Santa Barbara, California.
- 1 January Flooding in the Rhine River strikes Cologne.
- Iranian and Afghan armies defeat armed militias of Afghan Democratic Republic, marking its disbandment
- West Galician Crisis
- 7 March – A Richter Scale 7.6 magnitude earthquake kills at least 2,925 at Toyooka and Mineyama area, western Honshu, Japan.
- 22 April – 5 May – The Great Mississippi Flood of 1927 affects 700,000 people in the greatest national disaster in U.S. history at that time.
- 22 May - An 8.6 magnitude earthquake in Xining, China kills 200,000.
- 11 July - An earthquake strikes Palestine, killing around 300. The effects are especially severe in Nablus, but damage and fatalities are also reported in many areas of Palestine and Trans-Jordan such as Amman, Salt and Lydda.
- VIII Olympic Games in Amsterdam (Netherlands)
- II Winter Olympic Games in St. Moritz (Switzerland)
- Invasion of Cuba by the US
- Staten-Generalen of the Netherlands approves the Charter of the Federation of the East Indies
- multi-event sports event of Spartakiad 1 in Berlin (Germany)
- Inauguration of the Associated Free State of Cuba
- The Treaty of Recognition signed between Iran, Federation of Socialist Republics and Socialist Union of Turkestan normalizes diplomatic relationships
- 2. Workers' Olympiad in Antwerp (Netherlands)
- March Republican Herbert Hoover is sworn a second term as President of the United States.
- August - Signing of the Refugee Convention and establishment of the International Refugee Organization
- multi-sport event of Spartakiad 2 in Moscow (Russian FSR)
- First Siamese Revolution of 1930 (Thailand)
- 6 May – The Great Salmas Earthquake in Iran (7.3 on the Richter Scale) kills 4,000 people.
- June - US Congress approves Tariff Act of 1930
- 20 August - Great Economic Depression (also known as the Wall Street Crash)
- 25 November – An earthquake in the Izu Peninsula of Japan kills 223 people and destroys 650 buildings.
- 19 December – Merapi volcano in the island of Java (East Indies) erupts, killing 1,300.
- IAB becomes the secretariat and liaison office of the International Peasants' Union
- Egyptian Crisis
- The Nordic Monetary Union is created
- Second Republic of China invades and occupies Tibet
- 31 March – An earthquake destroys Managua, Nicaragua, killing 2,000 people.
- June - Conference on European Union in Brussels (Belgium)
- July The Huang He floods kill between 850,000 and 4,000,000 people
- 31 August – The Yangtze River floods, leaving 23 million homeless.
- Irish Free State, referendum that approves republican constitution severing all ties to the King and Parliament of the United Kingdom. Also withdraws membership to the Imperial Commonwealth Federation.
- IX Olympic Games in Tokyo (Japan)
- III Winter Olympic Games in Oslo (Norway)
- Arab Rebellion of Palestine
- Government of India Act 1932 creates the Federation of India
- 25 December – An earthquake in the Kansu Province in China kills 70,000.
- 3. Workers' Olympiad - Summer Games in Workers' Olympiad and Winter Games in Prague (Austria-Hungary)
- Japanese puppet state of Mengjiang established.
- March Farmer-Labor Franklin Delano Roosevelt is inaugurated as the 31th President of the United States.
- 3 March A powerful earthquake and tsunami hit Honshū, Japan, killing some 3,000.
- 25 August August 25 – The Diexi earthquake shakes Mao County, Sichuan, China and kills 9,000 people.
- 15 December, Queen Wilhelmina signs into law the Charter of the Kingdom of the Netherlands and the Commonwealth of States.
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