List of national border changes since World War I
List of national border changes since World War I refers to changes in borders between [nations] during or since 1914. For information on border changes from the end of the Napoleonic Wars to 1914, see List of national border changes from 1815 to 1914. This is a list of significant boundary changes with countries. This refers to where there have been changes in borders only, not necessarily including changes in ownership of a territory. For instance many European colonies in Africa became independent without any adjustment to their borders, although some did have many changes. Also mentioned are some de facto changes, not recognized by the international community, like Crimea.
- 1919 — The treaty of Versailles divides Germany's African colonies into mandates of the victors (which largely become new colonies of the victors). Most of Cameroon becomes a French mandate with a small portion taken by the British and some territory incorporated into France's previously existing colonies; Togo is mostly taken by the British, though the French gain a slim portion; German East Africa was separated between Belgium (Rwanda and Burundi), Portugal ( the Kionga Triangle ) and the United Kingdom (Tanganyika, later merging with Zanzibar to form Tanzania); and German South-West Africa (Namibia) becomes a mandate of South Africa. In September, France settles its African colonial borders with Italian Libya. On September 8, following the signing of the Anglo-French Convention of September 8, 1919, the borders of Italian Libya and French Chad are settled to the present-day boundaries. A few days later, the borders of western and southwestern Libya are extended to their current boundaries after French concessions with the Franco-Italian Arrangement of 12 September 1919.
- 1923 — the city of Tangier becomes an International Free Zone after France and Spain end their control over parts of the city.
- 1924 — Britain ceded a portion of Jubaland to Italy (Trans-Juba, it. Oltregiuba) as a reward for the Italians having joined the Allies in World War I.
- 1925 — The eastern borders of Libya and British Egypt are changed to their present boundaries, with the exception of parts of present-day southern Libya still remaining part of British Sudan.
- 1931 — France moves the control of the area of the present day Borkou-Ennedi-Tibesti Prefecture from the territory of Niger in French West Africa to Chad in French Equatorial Africa. Prior to this the territory of the modern-day state of Chad was split in half between the two federations.
- 1934 — The borders of Libya are changed to their present-day boundaries after the Italo-British-Egyptian Agreement, British Sudan cedes northern territory to Libya.
- 1935 — The Franco-Italian Agreement cedes the Aouzou Strip from French Chad to Italian Libya.
- 1936 — After the success of Italy during the Second Italo-Abyssinian War, Ethiopia is annexed by Italy. Ethiopia joins with Eritrea and Italian Somaliland to form Italian East Africa. The international community does not accept Italy's occupation of Ethiopia and maintains relations with exiled Ethiopian Emperor Haile Selassie.
- World War II — With the outbreak of World War II, war arrives in Africa in 1940, with Italy joining the war, initially British forces in British Somaliland are defeated by the Italians coming from Italian East Africa and the territory is taken. However, by 1941, the British retake lost territory and take over Italian East Africa. In North Africa, after a period of retreat into Libya, Italian forces receive vital aide from the German army and the Germans move deep into Egypt by 1942, before beginning to lose ground. By 1943, The German and Italian forces retreat from Libya and capture Tunisia from France prior to fleeing to Sicily.
- 1952 — After the WWII, Ethiopia was granted Eritrea.
- 1953 August 1 — Federation of Rhodesia and Nyasaland established from the British self-governing colony of Southern Rhodesia and the British protectorates of Northern Rhodesia, and Nyasaland.
- 1956 March 2 — French Morocco, the International Zone of Tangier, and most of Spanish Morocco join to become the independent nation of Morocco; December 13 — British Togoland joins with the Gold Coast before becoming the independent nation of Ghana in 1957.
- 1958 — French West Africa splits into Mauritania, Senegal, French Sudan (now Mali), French Guinea (now Guinea), Côte d'Ivoire, Niger, Upper Volta (now Burkina Faso) and Dahomey (now Benin)
- 1960 — Belgian Congo is granted independence as the Republic of the Congo. In 1964 it changes its name to the Democratic Republic of the Congo to differentiate itself from Congo-Brazzaville.
- 1960 July 1 — State of Somaliland (formerly British Somaliland) joins with Italian Somaliland to form Somalia. French Equatorial Africa's interim successor, the Union of Central African Republics dissolves in August with independence of Chad (August 11), Oubangui-Chari (now Central African Republic) (August 13), Congo-Brazzaville (now the Republic of the Congo) (August 15), and Gabon (August 17).
- 1961 May 31 — the northern two-thirds of British Cameroons joins Nigeria; October 1 — the southern third of British Cameroons joins with the Republic of Cameroon to form the Federal Republic of Cameroon. This year also the tiny Portuguese outpost of São João Baptista de Ajudá was annexed by Dahomey (now Benin)
- 1962 July 1 — The Belgian colony of Ruanda-Urundi separated into Rwanda and Burundi.
- 1963 December 31 — Federation of Rhodesia and Nyasaland dissolved; over the next two years Nyasaland becomes independent Malawi, Northern Rhodesia wins independence as Zambia, and Southern Rhodesia (or simply Rhodesia) unilaterally declares independence.
- 1964 — Tanganyika unites with the island of Zanzibar to form Tanzania.
- 1967 May 30 — The break-away state of Biafra is formed from southern Nigeria. Officially Biafra receives de jure acknowledgement of existence by only a few nations, but has the de facto support of France, Israel, Portugal, and South Africa which provide arms to the state in its war of independence against Nigeria.
- 1969 January 4 — Spain returns Ifni to Morocco.
- 1970 January 15 — Biafra is occupied and annexed by Nigeria.
- 1975 December — Spanish Sahara divided between Morocco and Mauritania (although Spain's formal mandate did not end until February 26, 1976)
- 1977 — South African Government reimposed direct rule on Walvis Bay.
- 1979 — Mauritania withdraws from southern Western Sahara, which is taken over by Morocco
- 1990 — Namibia gets independent from occupying South Africa.
- 1991 May 18 — Somaliland declares independence from Somalia but is not recognized by any other country.
- 1993 May 24 — Eritrea breaks off from Ethiopia.
- 1994 February 28 — Walvis Bay formally transferred by South Africa to Namibia.
- 2011 July 9 — South Sudan formally obtains independence from The Republic of Sudan.
- 1921 — The Soviet satellite state of Tannu Tuva is formed after Bolshevik revolutionaries take the region by force from Mongolia
- 1922 — The Saudi-Iraqi neutral zone is created.
- 1928 — The ICJ awards the Island of Palmas from the Philippines to the Dutch East Indies.
- 1932 February 18 — The Empire of Japan declares Manchukuo independent of China
- 1936 May 12 — Japan declares Mengjiang independent of China.
- 1938 — The British split Burma off from the rest of India. Hatay State, a city-state, is formed when it separates from French-held Syria.
- 1939 — Hatay joins Turkey.
- World War II — In the early stages of World War II in the Pacific, Japan made steady gains against the Allies. In 1940, with the collapse of France in Europe, the new Vichy regime allows Japan to annex French Indochina. After the attack on Pearl Harbor, Japan proceeds to occupy Wake Island, the Philippines, British Malaya, the Dutch East Indies, northern New Guinea and a number of pacific islands. Also Japan begins attacks against British-held Burma and India, and creates a puppet regime in Burma. From 1943 to its defeat, Japan steadily loses territory in the Pacific to the Allies and in 1945, Japan surrenders, abolishing its remaining puppet regimes in Manchukuo and Menjiang, and abandoning its hold on Korea.
- 1944 — Tuvinian People's Republic becomes a part of the Soviet Union.
- 1945 — The Republic of China annexes Taiwan
- 1946 April 1 — Straits Settlements, Unfederated Malay States and Federated Malay States join to form the Malayan Union. (Although these could have been considered remaining part of British Malaya). Jordan becomes independent after separating from the British Mandate of Palestine. The Turtle Islands is awarded by Britain to the Philippines.
- 1947 August — The Partition of India as India and Pakistan are given independence from Britain
- 1948 — The State of Israel is created after the 1947 United Nations General Assembly Resolution 181 called for the partition of the British-ruled Palestine into a Jewish state and an Arab state. The resolution was accepted by the Jews in Palestine, but rejected by the Arabs in Palestine and the Arab states.
- 1948 — After the Indo-Pakistani War of 1947–1948 over Kashmir, a Line of Control is created in Kashmir, creating Indian and Pakistani controlled zones.
- 1949 — The Republic of China loses control of all of mainland China (expect Kinmen and Matsu of Fukien province) to the newly formed People's Republic of China in the Chinese Civil War
- 1949 — The Arab–Israeli War ends in armistice, with Israel gaining 60% of the Palestinian state proposed by the 1947 partition plan, Egypt gaining the Gaza Strip and Jordan gaining the West Bank.
- 1950 — Chandannagar is taken over by India from French control.
- 1953 — Following the Korean War, the boundary between North Korea and South Korea is the Military Demarcation Line, which roughly follows the previous 38th parallel
- 1954 — Bands of Indian irregulars took over the Portuguese enclaves of Dadra and Nagar Haveli. On June 13, the port of Mahé breaks away from French rule and joins India. French Indochina dissolves, and the nations of Cambodia, Laos, and Vietnam become independent states.
- 1960 — Cyprus declares its independence from the United Kingdom. The Sovereign Base Areas of Akrotiri and Dhekelia are established on the island of Cyprus by the United Kingdom.
- 1961 December 19 — India takes over the Portuguese colony of Goa, Daman and Diu, which becomes a single Union Territory of India. In 1987, Goa is elevated to full statehood, with Daman and Diu remaining a Union Territory.
- 1962 August 16 — India officially absorbs the French enclaves of Pondicherry.
- 1962 — The Federation of South Arabia is created.
- 1963 — The Protectorate of South Arabia is created.
- 1963 — Pakistan cedes claimed areas of Kashmir to the People's Republic of China.
- 1963 September 16 — Singapore, British North Borneo (renamed Sabah), Sarawak and Malaya join to form Malaysia
- 1965 August 9 — Singapore withdraws from Malaysia
- 1965 — Jordan and Saudi Arabia concluded a bilateral agreement that realigned and defined the boundary.
- 1967 — The Federation of South Arabia and the Protectorate of South Arabia join to form South Yemen.
- 1967 — following the Six-Day War, Israel gains Sinai Peninsula and Gaza Strip from Egypt, West Bank from Jordan and Golan Heights from Syria.
- 1969 December 18 — Saudi–Kuwaiti neutral zone partitioned between Kuwait and Saudi Arabia
- 1971 December 16 — Bangladesh becomes independent.
- 1975 May 16 — Sikkim becomes part of India.
- 1976 July 2 — South Vietnam and the North Vietnam were officially unified as Vietnam
- 1976 July 17 — After being relinquished by Portugal in 1974, and invaded by Indonesia in 1975, East Timor is annexed by Indonesia
- 1982 — pursuant to the Camp David Accords, Israel completes the withdrawal from the Sinai Peninsula.
- 1990 May 22 — North Yemen unites with South Yemen. August 2 — Kuwait annexed by Iraq
- 1991 February 27 — Kuwait liberated from Iraq; Saudi–Iraqi neutral zone is officially recognized as being disbanded, it was de facto disbanded since 1981.
- 1994 - Under the Oslo Agreements, Israel transferred parts of the West Bank (Areas "A" and "B") and the majority of the Gaza Strip to the rule of the Palestinian National Authority.
- 1997 July 1 — Hong Kong transferred to People's Republic of China by Britain as a special administrative region.
- 1999 December 20 — Macau transferred to People's Republic of China by Portugal as a special administrative region.
- 2002 May 20 — East Timor gains independence from Indonesia.
- 2005 August — Israel dismantles its settlements in the Gush Katif region of the Gaza Strip, and the remainder of the Gaza Strip, most of which had already been transferred to Palestinian rule in 1994, became administered by the Palestinian Authority, until 2007 when the territory was seized by the military wing of Hamas in a violent coup d'état.
- 2015 June — India and Bangladesh border is removed of enclaves and exclaves.
- 1918 — Poland, Latvia, Lithuania, and Estonia declare their independence from the Russian Empire. Russia recognizes the independence of Finland, declared in 1917. The Kingdom of Slovenes, Croats and Serbs (later known as the Kingdom of Yugoslavia) is formed.
- 1919–20 — The Austro-Hungarian Empire is formally dissolved by the Treaty of Saint-Germain signed September 10, 1919 and the Treaty of Trianon signed June 4, 1920. Austria, Hungary, and Czechoslovakia are formed. Territory of the former kingdom is additionally awarded to Italy, Poland, Romania, and Yugoslavia. In 1919, Germany suffers substantial territorial losses in the Treaty of Versailles. Belgium receives Neutral Moresnet and three German cantons as compensation for extensive damage during World War I. These three cantons still form the German speaking community of Belgium: Eupen, Malmedy and Sankt Vith. Denmark receives Northern Schleswig from Germany (with local plebiscites concluding in 1920). Most of the Prussian provinces of Posen and of West Prussia were returned to Poland. The east part of Upper Silesia and the area of Soldau in East Prussia are annexed to Poland as well. Danzig and Saarland fall under the control of the League of Nations. The Memel territory comes under a temporary French administration.
- 1920 — Greece is promised most of eastern Thrace as well as Ionia with the city of İzmir (Smyrna) in the Treaty of Sèvres. The Free State of Fiume is established as the result of an Italo–Yugoslav border dispute.
- 1922 — The Soviet Union is officially formed under the Treaty on the Creation of the USSR. In December, the Irish Free State and United Kingdom of Great Britain and Northern Ireland are formed from the United Kingdom of Great Britain and Ireland. The United Kingdom maintains Treaty Ports at Berehaven, Cobh, and Lough Swilly.
- 1923 — The Treaty of Sèvres is superseded by the Treaty of Lausanne under which Greece loses its earlier territorial gains and the borders of modern Turkey are established. Western Thrace is ceded by Bulgaria to Greece, a decision earlier agreed upon in the 1919 Treaty of Neuilly-sur-Seine. On the Baltic sea, Lithuania annexes the Memel territory without plebiscite. Italian military forces take control of the Greek island of Corfu.
- 1924 — The Treaty of Rome is concluded on January 27, ending the existence of the Free State of Fiume and the Italo–Yugoslav border dispute. The treaty assigns Fiume (Rijeka) to Italy and Sušak to Yugoslavia, with joint port administration. On March 16, Italy formally annexes Fiume.
- 1926 — Albania cedes territory to the Kingdom of Slovenes, Croats and Serbs.
- 1929 — Vatican City becomes independent after the signing of the Lateran Treaty with Italy.
- 1935 — Saar is annexed by Nazi Germany after a plebiscite was held.
- 1938 — Austria is annexed by Nazi Germany in the Anschluss with plebiscite but also with a pre-vote invasion. On April 25, the United Kingdom returns the Treaty Ports to Ireland as part of the Anglo-Irish Trade Agreement. The Munich Agreement on September 29 permits Germany to also annex the Sudetenland region of Czechoslovakia.
- 1939 — The Memel territory is ceded to Nazi Germany by Lithuania under pressure from Berlin on March 23. The rest of Czechoslovakia is taken over by Nazi Germany, a German protectorate called Bohemia and Moravia is formed on the remaining Czech land, while Slovak territory is split between a puppet state of Slovakia and land given to Hungary. On August 23, the Molotov–Ribbentrop Pact is signed. Nazi Germany and the Soviet Union invade Poland on September 1.
- World War II — Many boundary changes occurred during the Second World War as Axis powers and the Soviet Union re-divided the areas under their control.
- 1945 — Following the war, the borders of Germany were moved west to the Oder-Neisse line, while the approximate boundary of the Curzon Line was used as the eastern border of Poland. In addition to incorporating the Kresy territories, the Soviet Union also annexed the Baltic states, Carpathian Ruthenia from Czechoslovakia, and Bessarabia, Hertza, and part of Bukovina from Romania. From Germany, the Soviet Union acquired the northeastern third of the former East Prussian exclave with the Klaipeda/Memel region becoming part of the Lithuanian SSR and the bulk of the territory forming the Kaliningrad Oblast of the Russian SFSR. Additionally, Finland ceded major portions of Karelia and Salla to the Soviet Union as well as islands in the Gulf of Finland, the whole Petsamo, and a lease to use Porkkala as a Soviet naval base for 50 years.
- 1947 — In the Paris Peace Treaties of 1947, Italy cedes the Dodecanese to Greece and Goriška, Inner Carniola, most of Istria, Zadar, its Dalmatian islands (such as Cres and Lastovo), and Rijeka (Fiume) to the newly established Socialist Federal Republic of Yugoslavia. Trieste, becomes the capital city of the Free Territory of Trieste established as an independent Sovereign State at the coming into force of the Treaty (September 15). 
- 1949 — April 23, Federal Republic of Germany cedes the villages Elten and Tüddern to the Netherlands.
- 1949 — May 23, the Federal Republic of Germany (West Germany) is formed and shortly afterwards, the German Democratic Republic (East Germany) is established on October 7.
- 1955 July 27 — Austrian State Treaty comes into force, established Austria from the four occupation zones of the Allied powers.
- 1956 — The Soviet Union returns Porkkala to Finland.
- 1957 — With plebiscite, Saar is incorporated into the Federal Republic of Germany, having previously bordered Luxembourg, France and West Germany.
- 1964 — Malta is independent from the United Kingdom.
- 1972 — The United Kingdom formally annexes Rockall (by the Island of Rockall Act 1972, declaring it to be part of Scotland).
- 1974 — After an attempted Greek Cypriot coup sponsored by the Greek military junta of that period, Turkey invades and occupies one-third of Cyprus.
- 1983 — The Turkish Republic of Northern Cyprus is declared but is not recognized by any country except Turkey.
- 1990 — East Germany reunites with West Germany on October 3. Transnistria declares independence from the Moldavian SSR but is not recognized by any country.
- 1991 — With the dissolution of the Soviet Union, the USSR is split up into 15 independent states, including the European states of Belarus, Estonia, Latvia, Lithuania, Ukraine and Moldova. All the former Soviet republics had their independence recognized by December 26. Slovenia (June 25), Croatia (June 25) including in their new borders former "zone B" of the Free Territory of Trieste, and the Republic of Macedonia (September 8) all declare their independence from Yugoslavia.
- 1992 — Bosnia and Herzegovina declares independence from Yugoslavia on March 1 and is formally recognized on April 6. The remaining rump of Yugoslavia becomes the Federal Republic of Yugoslavia (renamed Serbia and Montenegro in 2003).
- 1993 January 1 — Czechoslovakia is dissolved into the Czech Republic and Slovakia in the "Velvet Divorce".
- 2003 — Vištytis swap between Russia and Lithuania
- 2006 June 8 — The State Union of Serbia and Montenegro is dissolved. Montenegro and Serbia each become independent states.
- 2008 February 17 — Kosovo declares independence from Serbia and is recognized by a majority of UN member states including the United States, most western European states, Turkey, and Canada, though its independence is not recognized by Serbia, Greece, Spain, India, Russia, and the People's Republic of China.
- 2014 March 18 — Russia annexes Crimea from Ukraine, following an internationally unrecognized plebiscite.
- 2016 November 28 - Belgium and the Netherlands swapped landed near Lanaye and Oost-Maarland over the discovery of a headless body several years prior, which the Belgian Authorities could not access without crossing Dutch territory. The border has been straightened out and now runs down the center of the Meuse River.
- 1927 April 1 — The Imperial Privy Council of the United Kingdom establish the boundaries of the Dominion of Newfoundland and Canada, in particular, the province of Quebec, which transfers territories claimed by Quebec to Newfoundland. Previous maps showed the disputed territory as undefined.
- 1949 March 31 — The Dominion of Newfoundland joins with Canada. The territory is now called Newfoundland and Labrador.
- 1999 — Panama Canal Zone returned from joint US–Panamanian control to Panamanian control (the actual change in borders could also be regarded as the 1979 change from US control to joint US–Panama control).
- 2010— The Netherlands Antilles is dissolved, with Curaçao and Sint Maarten becoming constituent countries of the Kingdom of the Netherlands, while Bonaire, Saba and Sint Eustatius become special municipalities of the Netherlands.
- 1938 — A ceasefire signed between Paraguay and Bolivia awards Paraguay three-quarters of the Chaco Boreal which it took over during the Chaco War (1932–35).
- 1941 — The Rio Protocol recognises Peru as having control of the territory it won in the Ecuadorian–Peruvian war.
- 1949 July — Territory of New Guinea joins with the Australian Territory of Papua to form The Territory of Papua and New Guinea.
- 1955 November 23 — Cocos (Keeling) Islands transferred from the Singapore to Australia.
- 1957 — Christmas Island transferred from the Singapore to Australia.
- 1969 — Western Papua becomes part of Indonesia under the 1969 Act of Free Choice.
World maps showing borders
(Click to enlarge)
National boundaries around the time of the start of the First World War (1914)
Boundaries during the Second World War in November 1942, at the height of Axis power, especially in Europe.
National boundaries in 1985, during the Cold War
- "International Boundary Study No. 10: Libya–Sudan Boundary" (PDF)., United States Department of State, October 16, 1961
- "International Boundary Study No. 1: Algeria–Libya banaba" (PDF)., United States Department of State, April 28, 1961
- "International Boundary Study No. 3 (Revised): Chad–Libya Boundary" (PDF)., United States Department of State, December 15, 1978
-  Archived January 12, 2006, at the Wayback Machine.
- Timeline: Papua New Guinea, BBC News Online, May 5, 2009