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Since World War I, there have been many changes in borders between nations, detailed below. For information on border changes from the end of the Napoleonic Wars to 1914, see the list of national border changes (1815–1914). Cases are only listed where there have been changes in borders, 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, such as Crimea, and South Ossetia.
1919–1922 — 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.
1925 May 15 — The Tangier International Zone is established after France and Spain end their control over parts of the city.
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.
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.
1940 – 1943 — 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 aid 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.
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.
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)
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.
2024 April 1 — Puntland announces its temporary independence from Somalia until constitutional disputes and internal issues are to be resolved. It has no other formal recognition.
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 Mengjiang, and abandoning its hold on Korea.
1945 — Following the war, the Soviet Union annexes the Southern Sakhalin and Kuril Islands from Japan according to the Yalta Conference, and Korea is divided into the two countries, South Korea and North Korea.
1948 — The State of Israel is created after the 1947 United Nations General AssemblyResolution 181 called for the partition of the British-ruled Palestine into a Jewish state and an Arab state. The resolution is accepted by the Jews in Palestine, but rejected by the Arabs in Palestine and the Arab states.
1960 — Cyprus declares its independence from the United Kingdom; the Sovereign Base Areas of Akrotiri and Dhekelia are established on the island by the United Kingdom under the latter's control.
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.
2005 August 1 — 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, becomes administered by the Palestinian Authority, until 2007 when the territory is seized by the military wing of Hamas in a violent coup d'état.
2020 — While Nagorno-Karabakh remained an internationally recognised territory of Azerbaijan, the four UN Security Council resolutions, adopted in 1993 and demanding immediate withdrawal of the Armenian occupying forces from all occupied regions of Azerbaijan, remained unfulfilled until 2020. In 2020, a new war erupted in the region, which saw Azerbaijan retake control of most of southern Karabakh (Fuzuli, Jabrayil, Zangilan, Qubadli, Hadrut districts) and parts of north-eastern Karabakh (Talish, Madagiz). A trilateral ceasefire agreement signed on 10 November 2020, ended the war and forced Armenia to return control of all of the remaining territories surrounding Nagorno-Karabakh.
1921 — As a result of winning a war against Soviet Russia, Poland gains territories east of the Curzon Line, inhabited essentially by Lithuanians, Belarusians, Poles, and Ukrainians.
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 February 22 — The Treaty of Rome comes into effect, 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 February 11 — The Vatican City becomes independent after the signing of the Lateran Treaty with Italy.
1938 April 25 — The United Kingdom agrees to return its three Treaty Ports to Ireland as part of the Anglo-Irish Trade Agreement over the course of the next several months.
1938 November 2 — Hungary is awarded southern Slovakia and parts of the Subcarpathian Rus' in the First Vienna Award. Shortly after, Poland seizes small border regions.
1939 March 14 — The Slovak part of Czechoslovakia declares independence with German support.
1939 September 1 — Fall of Poland — With the last battle over, the Polish territory is divided between Germany, Slovakia, the Soviet Union and Lithuania.
1939 November 1 and 2 — The remaining Polish lands are incorporated into the Ukrainian SSR and the Byelorussian SSR, following the approval of rigged election results by their respective Supreme Soviets.
1940 March 12 — The Soviet Union forces Finland to cede various territories in the Moscow peace treaty, ending the increasingly untenable Winter War.
1940 June 24 — The Franco-Italian Armistice is signed, awarding Italy a thin strip of land on the border. An additional 50 km demilitarized zone is established, in which Italian influence eventually amounts to a de facto annexation.
1940 June 28 — Romania is forced to give up Bessarabia to the Soviet Union with German pressure to fulfill their Ultimatum.
1940 August 30 — Hungary is awarded Northern Transylvania from Romania as part of the Second Vienna Award.
1940 August 2 — Luxembourg and the area of Alsace-Lorraine are put under civil administration and attached to adjacent Reichsgaue. While never formally incorporated, these areas were increasingly put under German Laws and are widely considered to have been fully annexed.
1941 April 10 — While the invasion is still ongoing, the Independent State of Croatia is proclaimed by Slavko Kvaternik. The country remains under partial joint Italian-German occupation.
1941 April 14 — The German-occupied parts of Slovenia are put under civil administration and attached to adjacent Reichsgaue. Similarly to Luxembourg and Alsace-Lorraine, these areas were never fully annexed, instead being set up in preparatation for eventual integration.
1941 April 24 — The Bulgarian Occupation zone and the territory to be annexed into Italian Albania is agreed upon after multiple meetings with Germany.
1941 May 3 — Italy issues a Royal Degree, annexing parts of Slovenia as the Province of Ljubljana.
1941 May 14 — Bulgaria annexes the occupied areas of Greece.
1941 May 18 — The main Treaty of Rome of 1941 settles the Dalmatian territory annexed by Italy from the Independent State of Croatia. Later treaties define their borders in Ljubljana and Italian-occupied Montenegro.
1941 June 30 — Bulgaria fully incorporates its occupied territories in Yugoslavia. As the war continues, Germany allows Bulgarian troops to occupy more territory to free up forces for the Eastern Front.
1941 August 1 — Following Operation Barbarossa, the Bialystok District is formed and put under Civil Administration, being attached to an adjacent Reichsgau, again in preparation for eventual annexation. It's expanded to include the city of Grodno three months later.
1941 December 9 — Finland re-integrates the territories lost in the Moscow Peace Treaty during the Continuation War.
1942 November 11 — Case Anton is executed, ending the nominal independence of Vichy France and placing the entire country under German-Italian military administration.
1943 September 10 — In response to the Italian surrender, Germany executes Operation Achse and invades their former ally, setting up a puppet state in northern Italy. In addition to taking over all territories previously under Italian occupation, Germany splits apart lands from the Italian Social Republic, forming the Operational Zones of the Adriatic Littoral and of the Alpine Foothills in northeastern Italy and attaching them to adjacent Reichsgaue.
1944 September 19 — The Moscow Armistice is signed between Finland and the Soviet Union, ending hostilities between the two countries. Finland is forced to return all territory previously ceded with the Moscow Peace Treaty in addition to Petsamo and a lease on Porkkala.
1945 — End of the War — With the total defeat of Germany, the war is finally over. All territorial changes made by the Axis Powers are fully reverted, with the notable exception of Bulgaria keeping Southern Dobruja.
1948 — Following the signing of the Moscow Protocol of 1948, the Soviet Union formally annexes some Danubian islands and the Snake Island in the Black Sea from Romania.
1955 April 23 — Italy and Switzerland modify the border in the zone of Lago di Lei
1955 June 27 — The Austrian State Treaty comes into force, establishing an independent Austrian state from the four occupation zones of the Allied powers.
1961 — An adjustment to the Meuse river between The Netherlands and Belgium results in three small packages of land being exchanged between the two countries.
1963 — The 1949 Dutch acquisitions of West German territory are almost completely reverted; the Duivelsberg remains permanently with the Netherlands.
12 February 1986 — France and the United Kingdom sign the Treaty of Canterbury, defining a land frontier between the two countries. This border becomes physical with the breakthrough of the Channel Tunnel on 1 December 1990.
1990 — East Germany unites with West Germany on October 3. Transnistria declares independence from the Moldavian SSR but is not recognised by any country.
2003 — Lithuania's share of Lake Vištytis increases to about 383 ha (about 22% from 2.2%) from a new border treaty with Russia.
2006 June 3 — The State Union of Serbia and Montenegro is dissolved following a referendum; Montenegro and Serbia each become independent states.
2008 February 17 — Kosovo unilaterally declares independence from Serbia. The declaration is strongly opposed by Serbia and recognised by just over half (101 out of 193) of UN member states.
2016 November 28 — Belgium and the Netherlands swap land 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 centre of the Meuse River. The change took effect on 1 January 2018.
Regions of Ukraine annexed by Russia since 2014 (Crimea) and 2022 (Donetsk, Kherson, Luhansk and Zaporizhzhia), with a red line marking the area of actual control by Russia on 30 September 2022.
2022 September 30 — Russia unilaterally declares the annexation of the Ukrainian oblasts of Luhansk, Donetsk, Zaporizhzhia, and Kherson. Similar to the annexation of Crimea in 2014, this border change is not recognised internationally.
North America
1927 April 1 — The Imperial Privy Council of the United Kingdom establishes the boundaries of the Dominion of Newfoundland and Canada, in particular, the province of Quebec, which affirmed that territories claimed by Quebec were part of Newfoundland. Previous maps showed the disputed territory as undefined.
1949 March 31 — The Dominion of Newfoundland joins Canada. The territory is now called Newfoundland and Labrador.
1962 August 6 — Jamaica gains independence from the United Kingdom.
1962 August 31 — Trinidad and Tobago gains independence from the United Kingdom.
1966 November 30 — Barbados gains independence from the United Kingdom.
1973 July 10 — The Commonwealth of The Bahamas gains independence from the United Kingdom.
1974 February 7 — Grenada gains independence from the United Kingdom.
1999 — Panama Canal Zone returns from joint US–Panamanian control to Panamanian control. A previous important development was the 1979 change from US control to joint US–Panama control, with plans for full Panamanian sovereignty at some point after that.
2023 May 26 — The Netherlands and France make an agreement to clarify the border in Sint-Maarten after a dispute in 2016, the treaty is not yet in effect.
1949 July 1 — The Territory of New Guinea joins with the Australian Territory of Papua to form The Territory of Papua and New Guinea. The union is an administrative one only and does not affect the separate position of the Territory of New Guinea as a territory governed by Australia as a United Nations trust territory.
1974 — A referendum is held in the British colony of the Gilbert and Ellice Islands. Per the results of the referendum, the colony was divided into two.
1975 September 16 — The Territory of New Guinea and the Territory of Papua which were in an administrative union under Australian governance with the name Papua New Guinea are unified as a single sovereign country called the Independent State of Papua New Guinea.
1979 — The Marshall Islands leaves the Trust Territory of the Pacific Islands, becomes an independent country while also an associated state with the U.S.
1979 — The Federated States of Micronesia formed from part of the Trust Territory of the Pacific, also independent as an associated state with the U.S.
1994 — The Republic of Palau is formed from the remainder of the Trust Territory of the Pacific, as an independent state associated with the U.S.
South America
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).
Manning, Patrick (1990). Slavery and African Life: Occidental, Oriental, and African Slave Trades. London: Cambridge University Press.
Lovejoy, Paul E. (2012). Transformations of Slavery: A History of Slavery in Africa. London: Cambridge University Press.
Martin Klein, "Slave Descent and Social Status in Sahara and Sudan", in Reconfiguring Slavery: West African Trajectories, ed. Benedetta Rossi (Liverpool: Liverpool University Press, 2009), 29.
"Vatican City turns 91". Vatican News. 11 February 2020. Retrieved 24 July 2024. The world's smallest sovereign state was born on February 11, 1929, with the signing of the Lateran Treaty between the Holy See and the Kingdom of Italy
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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
Present-day boundaries
