List of World Map Changes - 20th Century

1930s

December 1 — The Finnish Democratic Republic is created after the Soviet invasion of Finland
October 12 — The General Government for the Occupied Polish Territories is created in Nazi Germany
October 6 — Poland is partitioned between Nazi Germany and the Soviet Union
September 28 — The Republic of Poland falls as a government, being under Nazi German occupation
September 14 — The colonies of French Guiana, Guadeloupe, Inini, Martinique, and Saint Pierre and Miquelon merges into the colony of the French Antilles and Guiana
September 2 — The Free City of Danzig is taken over by Nazi Germany
September 1
- World War II begins with the German invasion of Poland
- The Japanese militarily occupied Mongol United Autonomous Government is renamed the Mengjiang United Autonomous Government
April 12 — Italy annexes the Albanian Kingdom
April 6 — The islands of Canton and Enderbury are put under the Canton and Enderbury Islands condominium of the United States and the United Kingdom
April 1 — The Spanish Civil War ends with the Spanish State completely takes over Spain from the Spanish Republic
March 18 — Carpatho-Ukraine is annexed by Hungary
March 15 — Czechoslovakia is partitioned into the German protectorate of Bohemia and Moravia, Slovakia, and Carpatho-Ukraine

September 30
- The Munich Agreement transfers the Sudetenland from Czechoslovakia to Germany and gives parts of Slovakia to Hungary
- The Czecholovak Republic is renamed the Czecho-Slovak Republic
September 7 — The area known as Hatay, becomes an independent Hatay State, from Syria
July 29 — The Australian Federal Capital Territory is renamed the Australian Capital Territory
March 28 — The Reformed Government of China is formed after the Japanese invade northern China
March 12 — Nazi Germany annexes the Federal State of Austria in the Anschluss
March 8 — The United States claims the Canton and Enderbury Islands
January 14 — Norway lays claims in Antarctica as Queen Maud Land and lies between 20° west and 45° east
January 12 — Tristan da Cunha becomes a dependency of the crown colony of Saint Helena, part of the United Kingdom

December 29 — Irish Free State is renamed Ireland
December 14 — Japanese invasion of China continues with the creation of the Provisional Government of the Republic of China
December 5 — The invasion of China by Japan continues with the invasion of Shanghai, creating the Dadao Municipal Government of Shanghai
November 22 — The Mongol Military Government is renamed the Mongol United Autonomous Government
April 1 — The following colonies are split from the latter:
- The Aden Settlement is separated from British India and is changed into the Aden Colony and Protectorate, in modern-day Yemen
- British Burma is separated from the British Raj

December 22 — The Anglo-Egyptian treaty of 1936 is ratified, and all British troops are withdrawn from Egypt, except for the Suez Canal Zone
December 5 — In the French Mandate of Syria, the Sanjak of Latakia is integrated into the Syrian Republic
December 2 — In the French Mandate of Syria, the Jabal ad-Druze is integrated into the Syrian Republic
October 14 — Spanish Guinea is taken over by Spanish Nationalist forces
September — Ifni and Spanish Sahara are taken over by Spanish Nationalist forces
August 6 — The British reassert their claim on Kanton Island
July 23 — The Spanish State claims to be the sole government of Spain
July 17 — Nationalist forces take over Spanish Morocco, starting the Spanish Civil War
June 1 — The Italian colonies of Eritrea, Ethiopia, and Italian Somaliland merge to form Italian East Africa
May 9 — The Ethiopian Empire is taken over by Italy as Italian Ethiopia after the Second Italo-Abyssinian War

November 25 — The East Hebei Autonomous Council is created in China after the invasion of East Hebei by Japan
November 15 — The U.S. territory of the Philippines becomes a semi-independent Commonwealth of the Philippines
November 3 — The Hellenic Republic is renamed the Kingdom of Greece after a coup d'état, which restored the monarchy
April 1 — The Territory of the Saar Basin is taken over by Nazi Germany
March 26 — Jarvis Island is transferred from the United Kingdom to the United States
March 21 — The Imperial State of Persia is renamed the Imperial State of Iran

October 15 — The Chinese Soviet Republic is taken back over by the Republic of China
October 7 — The Catalan State is taken back over by Spain
October 6 — The Catalan State declares independence from Spain
April 6 — The Kingdom of Tavolara cedes to Italy
March 1 — The State of Manchuria is renamed the Great Empire of Manchuria
February 16 — The Dominion of Newfoundland joins Canada as a dependency
February 6 — The Turkish Islamic Republic of East Turkestan is taken back over by the Republic of China
January 1 — The three Italian provinces of Cyrenaica, Tripolitania and Fezzan become united into the colony of Libya

November 12 — The Turkish Islamic Republic of East Turkestan
June 13 — The United Kingdom cedes Enderby Land and Victoria Land to Australia as the Australian Antarctic Territory
April 5 — Eric the Red's Land is ceded back to Denmark in Greenland
March 23 — The German Reich has a regime change, and Nazi Germany takes over, under the same name

October 3 — Independence of the British Mandate of Mesopotamia from the United Kingdom as the Kingdom of Iraq
September 23 — The personal union of the Kingdom of Nejd and Hejaz unify to form the Kingdom of Saudi Arabia
September 13 — The Socialist Republic of Chile is put back in control by the Republic of Chile
June 4 — The Republic of Chile falls, and the Socialist Republic of Chile takes over
February 18 — Japan takes over northern China, and creates the State of Manchuria

November 7 — The Chinese Soviet Republic is established by the Communist Party of China, in China as independent
July 10 — Norway claims territory on eastern Greenland as Erik the Red's Land
June 12 — The Australian territories of North Australia and Central Australia merge to form the Northern Territory
April 28 — The Catalan Republic is taken back over by Spain
April 14
- The Kingdom of Spain is renamed the Spanish Republic after a government change
- After a government change of Spain, the Catalan Republic declares independence from Spain
January 28 — France officially annexes Isla de la Pasión as Clipperton Island
January 15 — The Belgian concession of Tientsin

List of World Map Changes - 20th Century - 1930s