# List of proposed state mergers

This is a list of proposed state mergers, including both current and historical proposals originating from sovereign states or organizations. The entities listed below differ from separatist movements in that they would form as a merger or union of two or more existing states, territories, colonies or other regions, becoming either a federation, confederation or other type of unified sovereign state.

## Current proposals

| Proposed state | Component states | Continent | First proposed | Notes |
| United States of Europe | European Union | Europe | 1831 | Currently advocated for by Volt Europa, Democrats 66, NEOS (Austria), Democracy in Europe Movement 2025 and other Eurofederalist parties. |
| Samoa | American Samoa Samoa | Oceania | 1894 | Proposed unification of the two Samoas |
| Canada | Canada Turks and Caicos Islands | North America | 1917 | The proposed Canadian annexation of the Turks and Caicos Islands has been an ongoing political discussion between the two nations since Canadian Prime Minister Robert Borden first supported the idea in 1917. |
| China | People's Republic of China Republic of China | Asia | 1949 | Unification of the territories of the People's Republic of China and the Republic of China is the nominal goal of both governments, which both operate under the One-China policy. However, within the free area of the Republic of China, there is a sizeable movement to formally declare a Taiwanese state, led by the Democratic Progressive Party, which is currently in government. |
| Korea | Democratic People's Republic of Korea Republic of Korea | Asia | 1953 | Korean reunification has been a goal for both Koreas since the 1953 armistice agreement. However, proposed strategies vary between the two Koreas, with both proposing unification under one sociopolitical system while abandoning the other, similar to German reunification. In January 2024, the supreme leader of the DPRK, Kim Jong Un called for amending the constitution to remove references to cooperation and unification, as well as defining the territorial boundaries of the DPRK and adding an article designating the Republic of Korea as the most hostile state. |
| Isratin or Canaan | Israel Palestine (West Bank & Gaza Strip) | Asia | 1967 | Also known as the one-state solution, it is a proposed approach to create a bi-national state to resolve the Israeli–Palestinian conflict. |
| United India | India Pakistan Bangladesh | Asia | 1972 | The concept of an Indo-Pakistani Confederation advocates for a political confederation consisting of the sovereign states of India and Pakistan as a means of ending bilateral conflicts and promoting common interests in defence, foreign affairs, and cultural and economic development. While this idea does not propose to end the sovereign existence of either nation through reunification, it is aimed to resolve the conflicts afflicting the subcontinent since the partition of India in 1947. |
| Saint Martin | Saint Martin Sint Maarten | North America | 1990 | Proposed unification of the island. |
| Romania | Moldova Romania | Europe | 1991 | Due to the Russian Revolution, the Bessarabia Governorate declared secession in 1917 as the Moldavian Democratic Republic and united unconditionally with the Kingdom of Romania in 1918, before the Soviet occupation in 1940. After Moldova gained independence following the dissolution of the Soviet Union, unification of Moldova and Romania has been proposed which is supported by the Moldovan minorities according to polls and the Romanian Government. |
| Union State | Belarus Russia | Europe and Asia | 1999 | Russia and Belarus signed an agreement to form the Union State in 1999 aiming to continue deeper integration, possibly until unification. Belarusian President Alexander Lukashenko has refuted this idea, declaring that any attempt to annex Belarus would result in war. |
| East African Federation | Burundi DR Congo Kenya Rwanda Somalia South Sudan Tanzania Uganda | Africa | 2004 | Proposed political union between the eight member states of the East African Community. Federation was proposed in 2004, but in 2016 it was decided that confederation would be the short-term goal. South Sudan, the DR Congo and Somalia are not as integrated as the other five members, as South Sudan only gained independence from Sudan in 2011, the DR Congo joined the Community in 2022, and Somalia joined the Community in 2023. |
| Greater Albania | Albania Kosovo | Europe | 2008 | Since Kosovo's Independence from Serbia, talks have been made for Albania and Kosovo to unite into a Greater Albania due to Kosovo's majority ethnic Albanian population. |
| South Africa | South Africa Lesotho | Africa | 2010 | Proposed integration of Lesotho with South Africa. |

## Historical
### Early modern period

| Proposed state | Components | Time period | Successful? | Notes |
| Croatia–Hungary Union | Kingdom of Hungary Kingdom of Croatia | 1102–1526 1527–1918 | Yes | After a brief separation during Ottoman-Hungarian war, the union was restored on the Lands of the Hungarian Crown inner the Habsburg monarchy. |
| Swiss Confederation | Uri Schwyz Unterwalden | 1307 | Yes | Three cantons formed the initial Confederation in the 1307 Rütlischwur, followed by the 1315 Pact of Brunnen; ten more cantons joined over the life of the Confederacy. |
| Kalmar Union | Danish Realm Kingdom of Norway Kingdom of Sweden | 1397–1523 | Yes | The Kalmar Union was a personal union between the Kingdoms of Denmark, Norway, and Sweden. Established in 1397 under the rule of Queen Margaret I, the union aimed to create a single monarch ruling over these three kingdoms. |
| Dual monarchy of England and France | Kingdom of England Kingdom of France | 1422–1453 | Partial | Treaty of Troyes consolidate the English claims to the French throne, but then Treaty of Arras (1435) reject it during Hundred Years' War. |
| Denmark–Norway | Danish Realm Kingdom of Norway | 1524–1814 | Yes | |
| Polish–Lithuanian Commonwealth | Kingdom of Poland Grand Duchy of Lithuania | 1569 | Yes | Union of Lublin |
| Polish–Lithuanian–Muscovite Commonwealth | Polish–Lithuanian Commonwealth Tsardom of Russia | 1574–1658 | No | |
| Iberian Union | Crown of Castile Crown of Aragon Crown of Portugal | 1580–1640 | Yes | Portugal became part of the realms of the Spanish Habsburg (Casa de Austria) following the death of Henry I of Portugal but resumed its independence 60 years later. |
| Polish–Swedish union | Polish–Lithuanian Commonwealth Swedish Empire | 1592–1660 | Partial | After a brief union during Sigismund III Vasa's reign, the Swedes rebelled against Sigismund and rejected the pretensions of restoring it at the Treaty of Oliva. |
| Polish–Lithuanian–Ruthenian Commonwealth | Polish–Lithuanian Commonwealth Cossack Hetmanate | 1658–1659 | No | Treaty of Hadiach |
| Swedish–Lithuanian Union | Swedish Empire Grand Duchy of Lithuania | | No | Union of Kėdainiai |
| Kingdom of Great Britain | Kingdom of England Kingdom of Scotland | 1707 | Yes | Though having been ruled since 1603 in personal union when James VI, already king of Scotland, succeeded to the English crown, both countries remained separate sovereign nation states until 1707 when the Treaty of Union unified them into a single entity. |
| United States | Connecticut Delaware Georgia Maryland Massachusetts New Hampshire New Jersey New York North Carolina Pennsylvania Rhode Island South Carolina Virginia | 1775–1788 | Yes | Constitution of the United States is ratified by the Thirteen Colonies, replacing the Articles of Confederation and thereby forming a Federal government. |
| Dutch Republic | Dutch Republic United Belgian States | 1789–1790 | No | During the Brabant Revolution, Hendrik van der Noot, Prime Minister of the young Belgian state proposed incorporating the confederation into the Dutch Republic. Later Willem I admitted that his idea to unite the Low Countries under the United Kingdom of the Netherlands was influenced by van der Noot's proposal. |

### 19th century

| Proposed state | Components | Time period | Successful? | Notes |
| United Kingdom of Great Britain and Ireland | Kingdom of Great Britain Kingdom of Ireland | 1800 | Yes | Acts of Union 1800. Most of Ireland left the union as the Irish Free State in 1922, while Northern Ireland remained part of the United Kingdom. |
| Northern Confederacy | Connecticut Massachusetts New York New Hampshire New Jersey Pennsylvania Rhode Island Vermont Also invited: Lower Canada New Brunswick Newfoundland Colony Nova Scotia Prince Edward Island Upper Canada | 1804 | No | The Northern Confederacy was a conspiracy headed by Senator Timothy Pickering to separate the Northeastern United States and The British Colonies in North America into one Confederation. |
| United Kingdom of Peru, Chile and Rio de la Plata | United Provinces of the Río de la Plata Viceroyalty of Peru Upper Peru Old Fatherland (Chile) | 1810–1816 | No | Manuel Belgrano proposed to the Junta of Buenos Aires the project to establish a monarchical government to maintain the territorial integrity of the ex-Viceroyalty of the Río de la Plata (modern Argentina, Uruguay, Paraguay and Bolivia), and also expand that monarchy to modern Chile and Peru (which at the time were in control of Royalists and were considered incapable of independence from Spain by themselves). However, the plan was rejected for chauvinist reasons, as Argentinians did not want to have an Inca, not a Spanish Bourbun, as the proposed King, and also feared being dominated by the Peruvian elites and their reactionary tendencies. |
| United Kingdom of the Netherlands | Sovereign Principality of the United Netherlands Provisional Government of Belgium (1814) | 1815 | Yes | |
| Union between Sweden and Norway | Kingdom of Sweden Kingdom of Norway | 1814–1905 | Yes | |
| Habsburg Italian Confederation | Kingdom of Lombardy–Venetia Kingdom of Illyria Papal States Duchy of Parma, Piacenza and Guastalla Duchy of Modena and Reggio Grand Duchy of Tuscany Kingdom of Sardinia Kingdom of the Two Sicilies Duchy of Lucca Duchy of Massa and Carrara Principality of Monaco Republic of San Marino Republic of Cospaia | 1815 | No | Klemens von Metternich's proposal for an Italian Confederation at the Congress of Vienna were rejected by Italian nobility and Austrian nobility. |
| German Confederation | Austria Prussia Bavaria Hanover Saxony Württemberg Other German States | 1816–1866 | Yes | |
| Russo-Polish Union | Russian Empire Kingdom of Poland | 1815–1830 1914–1918 | Partial | Constitution of the Kingdom of Poland as a kingdom in personal union with the Tsar of Russia, until Russian complete annexation in a real union after the November Uprising. Again proposed by Tsar Nicholas II in World War I to gain Polish support for the Russian side at the Eastern Front, and maintained by some White Monarchists to gain Polish and Entente support against the Russian Revolution. |
| Gran Colombia | United Provinces of New Granada Second Republic of Venezuela Real Audiencia of Quito | 1819–1830 | Yes | |
| First Mexican Empire | First Mexican Empire Captaincy General of Guatemala | 1822–1823 | Yes | Central America was annexed into the First Mexican Empire. After the dissolution of the Empire only Chiapas choose to remain part of Mexico, the rest became the Federal Republic of Central America. Costa Rica in particular was split between inner factions in favor and against the annexation, ending in a Civil War. The pro-Mexican provinces declared membership but were not recognized by the pro-independence provinces. |
| Gran Colombia-Dominican unification | Gran Colombia Republic of Spanish Haiti | 1822 | No | Proposal of José Núñez de Cáceres and Antonio María Pineda Ayala who were unable to meet Simón Bolívar before the Haitian occupation of Santo Domingo, and thus, Gran Colombia rejected the offer to avoid a war with Haiti. |
| Haitian-Santo Domingo union | Haiti Captaincy General of Santo Domingo | 1822 | Yes | Haiti annexes the Spanish part of Hispaniola island. |
| Federal Republic of Central America | El Salvador Honduras Nicaragua Guatemala Los Altos Costa Rica | 1823–1841 | Yes | |
| Costa Rica | Costa Rica Nicoya | 1824 | Yes | Annexation of Nicoya |
| Hispano-American Confederation | Formally invited: Gran Colombia Peru Bolivia First Mexican Empire Federal Republic of Central America United Provinces of the Río de la Plata Chile Not invited, but considered: Paraguay Haiti Spanish Empire Invited, but not considered seriously:  Empire of Brazil United States British Empire Dutch Empire | 1825-1826 | No | Proposed at the Congress of Panama by Simón Bolívar, but rejected by fears of Bolivarian authoritarism and centralism from non-Colombian deputies that suspected a "Colombian Empire" in this project (or just due to enmity and distrust against Simon Bolivar from regional Caudillos and leaders). Also due to differences between supporters of how to do that union (conflicts between federalists, monarchists, liberals, conservatives, etc.). |
| Federation of the Andes | Gran Colombia Peru Bolivia | 1826 | No | Proposed merger of the countries liberated by Simón Bolivar into a single state. |
| Peru–Bolivian Confederation | Peru Bolivia | 1829–1836 | Yes | |
| Italian United Provinces | Duchy of Parma Duchy of Modena and Reggio Grand Duchy of Tuscany Romagna (part of State of the Church) | 1831 | Yes | |
| Rio Uruguay | Juliana Riograndense Uruguay | 1836 | No | Riograndense forces were financially and (indirectly) militarily supported by the Uruguayan government led by José Fructuoso Rivera. The Uruguayans had the intention of creating a political union with the Riograndense Republic to create a new stronger state. Juliana Republic was founded in 1839 and formed a confederation with Riograndense, but Juliana itself collapsed less than four months after its founding. |
| United States | United States Upper Canada | 1837–1838 | No | Rebellions of 1837–1838. Republicans in Upper Canada pursued annexation by the United States. |
| Papal-Italian Confederation | Papal States Kingdom of Sardinia Duchy of Parma Duchy of Modena and Reggio Grand Duchy of Tuscany Kingdom of the Two Sicilies Kingdom of Lombardy–Venetia | 1840s | No | After an initial interest from Pope Pius IX to lead the Italian nobility in a supranational confederation, the proposal from Vincenzo Gioberti was rejected for being Liberal and Nationalist (ideologies condemned by the Catholic social teaching) and specially due to Italian unification movement having a political leadership from Anti-clerical and Freemasonry groups. |
| Southeastern Federation | Second Republic of Yucatán State of Tabasco State of Chiapas | 1841–1842 | No | The second Republic of Yucatán emerged when the federal pact signed by Yucatán and endorsed in the Constitution of Yucatán of 1825 was broken by the centralist government of Mexico from 1835. In 1841 the state of Tabasco decreed its separation from Mexico and Miguel Barbachano, then governor of Yucatán, sent a commission headed by Justo Sierra O'Reilly to meet with Tabasco authorities to propose the creation of an independent federal republic from Mexico formed by Yucatán, Tabasco and Chiapas. The idea failed when Tabasco rejoined Mexico in 1842. |
| United Kingdom of Ecuador, Peru and Bolivia | Ecuador Peru Bolivia | 1846 | No | Plan by Juan José Flores to reconquer the former Bourbon Crown territories of the Viceroyalty of Peru. |
| United States | United States Republic of Texas | 1846 | Yes | Texas annexation |
| Confederated States of Plata | Argentine Confederation Estado Oriental del Uruguay Paraguay | 1850 | No | The Confederated States of the Río de la Plata were a State proposal devised by Domingo Faustino Sarmiento in the book Argirópolis or the capital of the confederated states of the Río de la Plata, with its capital on Martín García Island, would be founded. This idea did not prosper due to the historical changes produced by the battle of Caseros in 1852. |
| Danubian Confederation | Hungary Romania Vojvodina Croatia Slovakia | 1850 | No | The Hungarian Statesman Lajos Kossuth (1802–1894) attempted at different stages of his exile following the Hungarian War of Independence in 1849 to organize a Danubian Confederation. He intended to accommodate the forces of nationalism within the Danubian basin while preserving Hungary's territorial integrity and replacing Austria's position in the European balance of power |
| Federation of Central America | El Salvador Honduras Nicaragua | 1852 | Yes | Second attempt at unification that lasted for less than a month. |
| Liberia | Republic of Liberia Republic of Maryland | 1854–1857 | Yes | Republic of Maryland was officially named Maryland in Liberia during its independence referendum on 29 May 1854. |
| United Principalities of Moldavia and Wallachia | Principality of Moldavia Principality of Wallachia | 1859 | Yes | Unification of Moldavia and Wallachia; becomes Kingdom of Romania in 1881. |
| United Provinces of Central Italy | Duchy of Parma Duchy of Modena and Reggio Grand Duchy of Tuscany Romagna | 1859 | Yes | |
| Kingdom of Sardinia | Kingdom of Sardinia United Provinces of Central Italy | 1860 | Yes | |
| Belgium–Netherlands Confederation | Belgium Netherlands | 1860 | No | Belgian Prime Minister Charles Rogier proposed a personal union of Belgium and the Netherlands due to fear of French invasion. |
| Confederate States of America | State of South Carolina State of Mississippi State of Florida State of Alabama State of Georgia State of Louisiana State of Texas Commonwealth of Virginia State of Arkansas State of North Carolina State of Tennessee | 1861–1865 | Yes | American Civil War |
| Spanish Empire | Spanish Empire First Dominican Republic | 1861 | Yes | In 1861 general Pedro Santana asked Queen Isabella II of Spain to retake control of the Dominican Republic after a period of only 17 years of independence. Spain accepted his proposal and made the country a colony again. |
| Kingdom of Greece | Kingdom of Greece United States of the Ionian Islands | 1864 | Yes | Treaty of London (1864) |
| Balkan Federation | Kingdom of Yugoslavia Principality of Albania Kingdom of Bulgaria | 1865–1948 | No | First proposed in 1865. The idea was a response to the diminishing influence of the Ottoman Empire in the region. The idea of a united Balkan peninsula died off in mid 20th century following the Tito–Stalin split. |
| North German Confederation | Kingdom of Prussia Kingdom of Saxony Grand Duchy of Hesse Duchy of Mecklenburg-Schwerin Grand Duchy of Mecklenburg-Strelitz Grand Duchy of Oldenburg Saxe-Weimar-Eisenach Duchy of Anhalt Duchy of Brunswick Duchy of Saxe-Altenburg Saxe-Coburg-Gotha Saxe-Meiningen Various other small principalities and free cities | 1866 | Yes | Following the Austro-Prussian War of 1866 and the annexation by Prussia of Austria's northern German ally states Otto von Bismarck proposed to unify Prussia and its own German ally states into a single Federation. Consequently, the North German Constitution was adopted, with the provision that the southern German minor states could enter into the union when politically feasible. |
| South German Confederation | Bavaria Württemberg Baden Hesse-Darmstadt | 1866 | No | Proposed union of the southern German states that was discussed in the mid-19th century. The idea of a confederation emerged in the aftermath of the Austro-Prussian War of 1866, which resulted in the dissolution of the German Confederation and the emergence of the North German Confederation under the leadership of Prussia. The southern German states, including Bavaria, Württemberg, Baden, and Hesse-Darmstadt, were concerned about the growing power of Prussia and the dominance of northern German states in the new confederation. They sought to form their own union, which would allow them to retain their autonomy while also providing for mutual defense and economic cooperation. |
| Austro-Hungarian Empire | Austria Hungary | 1867 | Yes | Unification of Austro-Hungarian Empire |
| United States | United States Russian America | 1867 | Yes | Alaska purchased from the Russian Empire by the United States, became a department and territory before gaining full statehood in 1959. |
| Liechtenstein | Liechtenstein Russian America | 1867 | No | According to Prince Hans-Adam II, the Russian Empire proposed the purchase of Alaska to The Principality Of Liechtenstein. |
| Dominion of Canada | Province of Canada Province of New Brunswick Province of Nova Scotia | 1867 | Yes | Canadian Confederation |
| Antillean Confederation | Captaincy General of Cuba Captaincy General of Puerto Rico Second Dominican Republic | 1869–1870 | No | Proposed by Ramón Emeterio Betances. |
| Dominion of Canada | Dominion of Canada North-Western Territory Rupert's Land | 1870 | Yes | Following the British Crown acquiring the North-Western Territory and Rupert's Land from the Hudson's Bay Company it was transferred to the Dominion of Canada. |
| German Empire | Lesser Germany: North German Confederation Kingdom of Bavaria Kingdom of Württemberg Grand Duchy of Baden Grand Duchy of Hesse Alsace-Lorraine Greater Germany also included: Austrian Empire | 1871 | Yes | The German question regarding the competing ideas of "Greater Germany" and "Lesser Germany" (whether or not a united Germany should include the Austrian Empire) was settled with the Austro-Prussian War in 1866, in which Prussia assumed leadership of the various minor German nation states. The Unification of Germany (excluding Austria) was completed after German victory over the French in the Franco-Prussian War. |
| Austro-Hungarian-Bohemian Empire | Austro-Hungarian Empire Kingdoms of Bohemia | 1871–1918 | No | Franz Joseph I of Austria rejected proposals of Austro-Czech Compromise. His successor Karl I of Austria accepted those pretensions of reform in October 1918, shortly before his abdication, but were never implemented due to the Dissolution of Austria-Hungary. |
| Dominion of Canada | Dominion of Canada United Colony of British Columbia | 1871 | Yes | Following a merger of the Colony of British Columbia (1858-1866) and the Colony of Vancouver Island in 1866 the new colony was incorporated into Canadian Confederation in 1871 as the Province of British Columbia. |
| Dominion of Canada | Dominion of Canada Colony of Prince Edward Island | 1873 | Yes | Prince Edward Island joined Canadian Confederation partially to gain financial support from the union to avoid bankruptcy. |
| Bulgaria–Romania | Bulgaria Romania | 1878–1879 | No | Proposed personal union, German prince Alexander of Battenberg is elected instead. |
| Austro-Hungarian-Croatian Empire | Austro-Hungarian Empire Croatia (Triune Kingdom) | 1880–1918 | Partial | Trialism in Austria-Hungary isn't approved by the Diet of Hungary many times to maintain the Hungarian Crown intact, except on 1918 due to Karl I of Austria pression, but wasn't implemented due to Dissolution of Austria-Hungary after World War I. |
| United States of Peru–Bolivia | Peru Bolivia | 1880 | No | Proposed state by Nicolás de Piérola and Narciso Campero, also called the Federal Republic of the Incas. |
| Dominion of Canada | Dominion of Canada British Arctic Territories | 1880 | Yes | The British Arctic Territories, made of the Arctic Archipelago were transferred to the Dominion of Canada via the Adjacent Territories Order. |
| Kingdom of Spain | Kingdom of Spain Captaincy General of the Philippines | 1880–1898 | No | By the Propaganda Movement led by Filipinos educated in Europe which advocated the Philippine islands be converted from a colony to a province of Spain. |
| Estonian–Finnish federation | Estonia Finland | 1881–1941 | No | The matter was discussed on December 8, 1917, at the Estonian Council of Elders, where Jaan Raamot spoke about the positive attitude of Pehr Evind Svinhufvud, Speaker of the Senate of Finland. In his speech to the Council of Elders, Estonian Politician Konstantin Päts supported the Union and welcomed the idea. |
| Polynesian Confederation | Kingdom of Fiji Kingdom of Hawaii Kingdom of Samoa Kingdom of Tahiti Kingdom of Tonga | 1882 | No | During the period of European colonization, king Kalākaua of Hawaii proposed a Polynesian Confederation. |
| Principality of Bulgaria | Bulgaria Autonomous Province of East Rumelia | 1885–1886 | Yes | After Bulgaria defeated Serbia in the Serbo-Bulgarian War of 1885, Bulgaria nearly doubled in size when East Rumelia was incorporated within its borders. Bulgaria officially annexed it from the Ottoman Empire in 1885. |
| Bulgaria–Romania | Bulgaria Romania | 1886–1887 | No | Proposed personal union, rejected by Carol I of Romania due to Russian pressure. |
| Dominion of Canada | Dominion of Canada Jamaica | 1890 | No | In the late 19th century, there was some discussion of some form of political union between Canada and Jamaica. |
| Greater Republic of Central America | El Salvador Honduras Nicaragua Considered joining: Costa Rica Guatemala | 1895–1898 | Yes | |
| Anglo-American union | United Kingdom United States | 1860–1914 | No | Numerous prominent transatlantic thinkers proposed a union of the United States and the United Kingdom. |

### 20th century

| Proposed state | Components | Time period | Successful? | Notes |
| Commonwealth of Australia | New South Wales Queensland South Australia Tasmania Victoria Western Australia Also invited: Colony of Fiji Colony of New Zealand | 1901 | Yes | Federation of Australia. New Zealand had many disagreements with the Australian government and decided to not join. Fiji also did not join. |
| Saudi Arabia | Third Saudi State Jabal Shammar Kingdom of Hejaz Sharifian Caliphate Idrisid Emirate of Asir Sharifate of Mecca Sheikdom of Upper Asir Principality of Najran | 1901-1934 | Yes | Proclamation of the Kingdom of Saudi Arabia |
| Saudi Arabia | Saudi Arabia Kingdom of Yemen | 1934 | No | See also: Saudi–Yemeni war (1934) |
| Franco-British Union | France United Kingdom | 1904–1956 | No | A Franco-British Union is a concept for a union between the two independent sovereign states of the United Kingdom and France. Such a union was proposed during certain crises of the 20th century; it has some historical precedents. In April 1904 France and the United Kingdom signed a series of agreements, known as the Entente Cordiale, which marked the end of centuries of intermittent conflict between the two powers, and the start of a period of peaceful co-existence. Nationalist political leaders from both sides were uncomfortable with the idea of such a merging. |
| Oklahoma | Oklahoma Territory Cherokee Nation Choctaw Nation Chickasaw Nation Muscogee Nation Seminole Nation | 1904–1907 | Yes | The Five Civilized Tribes in Indian Territory did not want to unify with Oklahoma, and thus proposed to create a separate state as a means to retain control of their lands and some measure of independence. Their efforts culminated in the State of Sequoyah in 1905, but they failed to gain support in the U.S. Congress. Following annexation, the region was admitted to the union as the State of Oklahoma. |
| Union of South Africa | Cape Colony Colony of Natal Orange River Colony Transvaal Colony | 1909 | Yes | Union of South Africa |
| Imperial Federation | United Kingdom Ireland Dominion of Canada Commonwealth of Australia Dominion of Newfoundland Dominion of New Zealand Union of South Africa India | 1911–1937 | No | The British Empire was composed of many states with vastly different constitutions and goals to pursue. Groups like the Imperial Federation League advocated for a political union between the territories of the Empire that could establish a "permanent binding force" between them. Each dominion would be guaranteed representation on equal footing with the United Kingdom in an Imperial Parliament. Ireland would also have been presented representation as an alternative to home rule, and it was deemed possible that an autonomous India could one day join as well. First discussed by heads of government at the 1911 Imperial Conference, and for a second time at the 1937 Imperial Conference where it was eventually dismissed. |
| Dominion of Canada | Dominion of Canada The Bahamas | 1911 | No | In 1911, at the request of the Bahamian House of Assembly, the Canadian and the Bahamian governments began serious negotiations for Bahamian accession to the Canadian confederation. However, a racial panic ignited by the migration of over one thousand African-Americans fleeing violence in Oklahoma derailed the discussions. Prime Minister Wilfrid Laurier turned against the idea, citing incompatible "ethnical origin". After Laurier lost the September 1911 federal election, Bahamian Governor William Grey-Wilson travelled to Canada to reopen accession talks with newly elected PM Robert Borden. In a meeting between Grey and Borden on 18 October 1911, Borden rejected the possibility of taking the Bahamas into the Canadian confederation. His reasoning was that the events of the past year had proved that Canadian public opinion would not countenance the admission of a majority-black province. The British Colonial Office concurred: "No doubt for the moment the Dominion government would safeguard their interests, but there are signs of the rise of a colour question in Canada and in any case it cannot be long before U.S. opinion gives the tone to Canada in regard the Negro." |
| Kingdom of Greece | Cretan State Kingdom of Greece | 1913 | Yes | Crete rebelled against Ottoman rule during the Cretan Revolt of 1866–69 and used the motto "Crete, Enosis, Freedom or Death". The Cretan State was established after the intervention of the Great Powers, and Cretan union with Greece occurred de facto in 1908 and de jure in 1913 by the Treaty of Bucharest. |
| Austro-Polish Union | Projected: Austro-Hungarian Empire Kingdom of Poland Also considered: Western Ukraine | 1914–1918 | No | Proposals from Trialists to incorporate Russian Poland in the Habsburg empire, unifying them with Austrian Poland and turn them in a Third Crown like Austria and Hungary. Approved by Karl I of Austria in October 1918. Never implemented due to German empire plans over the Kingdom of Poland, and also Central Powers defeat at World War I. Also rejected by Polish nationalists due to some propossals of create an Eastern Galicia Kingdom governed by pro-Habsburg Ukrainian nobility. |
| Aistija | Latvia Lithuania | 1915-1940 | No | During World War I and the Interwar period, many Latvian and Lithuanian scholars, such as Jonas Šliūpas, argued that Latvia and Lithuania should unify as part of the Baltic Entente. This idea was originally proposed by Latvia and supported by Lithuania, especially after losing their capital Vilnius to Poland in the Polish–Soviet War, however it was eventually rejected by Lithuania because they would have to give up their claims on Polish land including Vilnius. The idea was still popular until the Occupation of the Baltic states, when it fell out of favour. |
| Habsburg Danubian Confederation | Proposed: Crown of Austria Crown of Hungary Crown of Croatia (Triune Kingdom and Bosnia-Herzegovina) Kingdom of Bohemia Kingdom of Galicia and Lodomeria Projected states to incorporate: Kingdom of Poland  Kingdom of Albania  Kingdom of Serbia  Kingdom of Montenegro  Kingdom of Romania | 1917-1918 | Partial | Karl I of Austria proposed reforms to Confederate the Habsburg monarchy (based in traditional kingdoms than nation-states) and also the possible incorporation of some Balkan States and Poland (or give Kingdom of Galicia to German puppet- Poland). Most of the Diets approved the proposals of Kaiser Karl I between October–November 1918 to avoid punishment from the Allies of World War I. Never implemented due to Dissolution of Austria-Hungary and also by Josephinists (Austrian Centralists), Pan-Slavist, Serbian irredentist, Czech nationalist, Polish nationalist, Hungarian nobility and Pan-Germanist opposition. |
| Danish–Icelandic Act of Union | Kingdom of Denmark Kingdom of Iceland | 1918–1944 | Yes | |
| Hungary–Romania | Kingdom of Romania Republic and Kingdom of Hungary | 1917–1920 | No | Federation or personal union between the Kingdom of Romania and the Kingdom/Republic of Hungary under one monarch. Proposals were the most active in 1919 and 1920, but they continued to exist up to the Second World War. |
| United States of Poland | Kingdom of Poland Kingdom of Lithuania Kingdom of Galicia and Lodomeria Belarusian Democratic Republic | 1917 | Partial | |
| Kingdom of Yugoslavia | Kingdom of Serbia Kingdom of Montenegro State of Slovenes, Croats and Serbs | 1918 | Yes | Creation of Yugoslavia |
| Kingdom of Romania | Kingdom of Romania Moldavian Democratic Republic Bukovina Transylvania | 1918 | Yes | Great Union, Union of Bessarabia with Romania, Union of Bukovina with Romania, Union of Transylvania with Romania |
| Intermarium | Belarusian People's Republic Czechoslovak Republic Estonia Finland Hungarian People's Republic Latvia Lithuania Polish Republic Kingdom of Romania Ukrainian People's Republic Kingdom of Yugoslavia Kingdom of Bulgaria | November or December 1918 | No | Also called "Międzymorze" in Polish. Suggested shortly after World War I to combat the influences of Germany and Russia. |
| Transcaucasian Democratic Federative Republic | Democratic Republic of Georgia Democratic Republic of Armenia Azerbaijan Democratic Republic | 1918 | Yes | A short-lived South Caucasian state that extended across what are now the modern-day countries of Georgia, Armenia and Azerbaijan plus parts of Eastern Turkey as well as Russian border areas. The state only lasted for a month before Georgia declared independence, followed shortly by Azerbaijan and Armenia. |
| Sweden | Sweden Aland | 1918 | No | See also: 1919 Ålandic status referendum |
| Weimar Republic | Weimar Republic Republic of German-Austria | 1918–1919 | No | Following the disintegration of Austria-Hungary in the final days of World War I the German-speaking territories of the former Austria-Hungary attempted to begin a process of integration into Weimar Germany. The Allies did not favor the idea, and forced the Austrian rump state to sign the Treaty of Saint Germain, which prohibited Austria from uniting with Germany. |
| Ukrainian People's Republic | Ukrainian People's Republic West Ukrainian People's Republic | 1919 | Yes | Act Zluky |
| Patria Grande | Argentina Bolivia Chile Colombia Costa Rica Cuba Dominican Republic El Salvador Ecuador Guatemala Honduras Mexico Nicaragua Panama Paraguay Peru Puerto Rico Uruguay Venezuela | 1922 | No | The concept of a shared homeland or community encompassing all of Spanish America, and sometimes all of Latin America and the Caribbean. The term is associated with political ideas of Ibero-American integration, rejecting the balkanization of the Spanish Empire in the Americas that followed the Spanish American wars of independence. The term may be also used to talk specifically about projects of Hispanic American unity held by Simón Bolívar and José de San Martín. |
| Union of Soviet Socialist Republics | Byelorussian SSR Russian SFSR Transcaucasian SFSR Ukrainian SSR | 1922 | Yes | Treaty on the Creation of the Union of Soviet Socialist Republics |
| Union of South Africa | Union of South Africa Colony of Southern Rhodesia | 1922 | No | The 1922 Southern Rhodesian government referendum was held in the colony on 27 October 1922. Voters, almost all of them White, were given the options of establishing responsible government or joining the Union of South Africa. After 59% voted in favour of responsible government, it was officially granted on 1 October 1923. |
| Baltoscandia | Denmark Sweden Finland Norway Iceland Estonia Lithuania Latvia | 1928–1960 | No | The term Baltoscandia was first used by Sten de Geer in an article in "Geografiska Annaler" in 1928 and further developed by Kazys Pakštas. He envisioned Baltoscandia as an economic, political and military unit. Kazys Pakštas proposed that one of the ways for the small nations to withstand the influence coming from the large ones is to unite and to cooperate more closely among each other. As he mentions, unification is possible only among nations that are similar by their size, geographical environment, religion and culture. |
| Greater Indonesia | Dutch East Indies British Malaya Kingdom of Sarawak British North Borneo Protectorate of Brunei British Singapore Portuguese Timor | 1928 | No | A political concept that sought to bring the so-called Malay race together by uniting the territories of Dutch East Indies (and Portuguese Timor) with the British Malaya and British Borneo. It was espoused by students and graduates of Sultan Idris Training College for Malay Teachers in the late 1920s, and individuals from Sumatra and Java including Mohammad Yamin and Sukarno in the 1950s. Indonesia Raya was later adapted as the name of the Indonesian national anthem in 1924. |
| German Reich | German Reich Federal State of Austria | 1938 | Yes | Anschluss |
| Turkey | Turkey Hatay State | 1939 | Yes | On 2 September 1938 the Sanjak of Alexandretta declared itself separate from the French Mandate of Syria and Lebanon, becoming the Hatay State. On 29 June 1939, the legislature voted to merge with Turkey. |
| Polish–Czechoslovak confederation | Polish Republic Czechoslovak Republic | 1939–1948 | No | Proposed by Władysław Sikorski. |
| Greek–Yugoslav confederation | Strictest definition: Kingdom of Greece Kingdom of Yugoslavia Loosest definition also includes: Albanian Kingdom Kingdom of Bulgaria Kingdom of Romania | 1942–1944 | No | The Greek-Yugoslav confederation was a political concept during World War II, sponsored by the United Kingdom and involving the Greek government-in-exile and the Yugoslav government-in-exile. The two governments signed an agreement pushing the proposal ahead, but it never got beyond the planning stage because of opposition from within the Greek and the Yugoslav governments, real world events, and the opposition of the Soviet Union. The proposal envisioned the creation of a confederation of Greece and Yugoslavia. |
| Soviet Union | Soviet Union Tuvan People's Republic | 1943–1944 | Yes | Tuvan underwent intense Russification of social and economic practices, and virtually all remaining opposition to Stalinist policy was eradicated. The Soviets desired the mineral resources of the republic and a permanent end to Mongolian-Chinese geopolitical intrigues in the region. This process culminated in the absorption of Tuva in 1944, under the rule of General Secretary Salchak Toka and his wife, Head of State Khertek Anchimaa-Toka. |
| Alpenland | Alsace South Baden Canton of Basel Bavaria Austria German-speaking Switzerland | 1945–1952 | No | Main article: Alemannic Separatism § Separatism After the end of World War II, there was a political movement in southern Alsace and South Baden, originating from resistance movements against the Nazi regime, which aimed for the creation of a separate Alemannic state together with the Swiss canton of Basel. Bernhard Dietrich, mayor of Singen, aimed at a larger "Alpine union" which was to include also Bavarian speaking territories (e.g. Bavaria and Austria) and the German-speaking parts of the Swiss Confederation. |
| United Arab Kingdom | Transjordan Palestine | 1945–1972 | No | King Hussein's federation plan: In the late 1940s and early 1950s, there were discussions of a potential merger between Palestine and Jordan, which was then known as Transjordan. The idea was initially proposed by King Abdullah I of Jordan, who sought to create a larger Arab state in the region that would include both Jordan and Palestine. The proposal was also supported by some Israeli politicians who believed that a union with Jordan would help to resolve the ongoing conflict between Jews and Arabs in the region. |
| Ewe Land | French Togoland British Togoland | 1945–1956 | No | In 1945 various members of Ewe and wider Togolese leadership began the construction of political organizations which sought to decolonize French Togoland. These developed as the Comité de l'Unité Togolaise, led by Sylvanus Olympio, and the Mouvement la Jeunesse Togolaise. Both possessed political platforms that included the reunification of the French Togoland and British Togoland. |
| Maghreb Federation | Algeria Libya Mauritania Morocco Spanish Morocco Spanish Sahara Tunisia | 1945–1958 | No | The first charter to create a Maghreb Federation was signed in Tunisia and Morocco in May 1945, but only became effective in 1958. |
| Balkan Federation | Socialist Federal Republic of Yugoslavia People's Socialist Republic of Albania People's Republic of Bulgaria | 1946–1948 | No | Josip Broz Tito came extremely close to persuading Albania to accept integration into Yugoslavia, but relations cooled in 1948 over fears that Yugoslavia only intended to use Albania for raw materials, subsequently resulting in the expulsion of Yugoslav diplomats. Yugoslav/Bulgarian negotiations fell through when Moscow attempted to force both countries into accepting Soviet control over the merge, which caused Yugoslavia to withdraw from negotiations and precipitated the Tito–Stalin split. |
| India | India Junagadh State Other states | 1947–1948 | Yes | Political integration of India, Annexation of Junagadh |
| United States of Indonesia | Bangka Banjar Biliton Central Java East Borneo East Indonesia East Java East Sumatra Great Dayak Indonesia Madura Pasundan South Sumatra Southeast Borneo Riouw West Borneo | 1946–1949 | Yes | Following discussions between Dutch authorities and Indonesian nationalist leaders, the Linggadjati Agreement was signed on 15 November 1946, in which the unilaterally declared Republic of Indonesia agreed to the principle of a federal Indonesia including the territory controlled by the Republic and other territory in the region which the Dutch controlled at that point. The Dutch then organised the December 1946 Denpasar Conference, which led to the establishment of the State of East Indonesia, followed by a state in West Borneo. Further states were set up in former territory of the Republic after they were conquered by the Dutch in 1947. Further Dutch military action faced increasing resistance from governments of the states they had established, and this combined with international pressure caused the Dutch–Indonesian Round Table Conference to take place in The Hague from August to November 1949. This Conference resulted in the Dutch agreeing to hand over sovereignty to a federal union of these states, which officially became the Republic of the United States of Indonesia. This federation lasted only a year, as its member states agreed to dissolve themselves into a unitary state, the last stage of which took place on 17 August 1950. |
| India | India Princely states | 1947–1950 | Yes | Instrument of Accession |
| Pakistan | Pakistan Princely states | 1947–1950 | Yes | Instrument of Accession |
| India | India Hyderabad | 1948 | Yes | Annexation of Hyderabad |
| Dominion of Canada | Dominion of Canada Dominion of Newfoundland | 1948–1949 | Yes | In two rounds of referendums in 1948, the Dominion of Newfoundland had the choice of becoming an independent state, merging with the Dominion of Canada, or remaining as a British dominion. The Newfoundland Act of 1949, an act of the Parliament of the United Kingdom, confirmed and gave effect to the Terms of Union agreed to between the then-separate Dominions of Canada and Newfoundland on 23 March 1949. |
| Netherlands–Indonesia Union | Netherlands United States of Indonesia | 1949–1956 | Partial | After the Netherlands had signed a truce with the United States of Indonesia, a transfer of sovereignty took place on 27 December 1949. As part of the Linggadjati Agreement, the Netherlands–Indonesia Union was founded. The Union was abolished when Indonesia left in 1956. |
| State of the Fertile Crescent | Jordan Iraq Syria Lebanon Palestine | 1949–1958 | No | Fertile Crescent Plan |
| Dominion of Canada | Dominion of Canada Bermuda | 1949 | No | In 1949 Henry Vassey, then Chairman of the Bermuda Trade Development Board, urged the House of Assembly of Bermuda to pursue a political union with Canada. Four Methodist church congregations in Bermuda are part of the United Church of Canada, forming Bermuda Presbytery of the United Church's Maritime Conference headquartered in Sackville, New Brunswick. The same Salvation Army Church territory serves both Canada and Bermuda with many of their pastors travelling between countries. In January 2009, Nova Scotia's Premier, Rodney MacDonald, and the Premier of Bermuda, Ewart Brown, signed a five-year agreement that would strengthen Nova Scotia's ties with Bermuda and enhance service export opportunities, tourism, transportation and health links in both jurisdictions. Bermuda's ties to Canada include the Institute of Chartered Accountants of Bermuda being overseen by Canada's Chartered Professional Accounting profession. |
| China | People's Republic of China Tibet | 1950–1951 | Yes | Chinese invasion results in the signing of the Seventeen Point Agreement and annexation of Tibet. |
| Franco-German Federation | West Germany France | 1950 | No | The idea of a Franco-German federation was a proposed merger between France and Germany after the end of World War II. The idea was promoted by French politician Robert Schuman in his declaration on May 9, 1950, which is now celebrated as Europe Day. The aim of the proposal was to create a lasting peace between the two countries and to promote economic cooperation. The Franco-German federation proposal envisioned a common government, currency, and military. It also sought to establish a European Coal and Steel Community (ECSC), which would integrate the coal and steel industries of France and Germany. The ECSC was created in 1952 and was the first step toward the creation of the European Union. |
| Greece | Greece Cyprus | 1950 | No | An unofficial referendum on enosis (reunification) with Greece was held in Cyprus between 15 and 22 January 1950, and the proposal was approved by 95.71% of those taking part. |
| Indonesia | Indonesia Netherlands New Guinea | 1950–1969 | Yes | Following Dutch recognition of Indonesian Independence, Indonesia continued to claim the remaining Dutch territory in the region, Netherlands New Guinea, as its rightful territory. The dispute escalated into low-level conflict in 1962 following Dutch moves in 1961 to establish a New Guinea Council. Facing diplomatic pressure from the United States, fading domestic support and continual Indonesian threats to invade the territory, the Netherlands decided to relinquish control of the disputed territory in August 1962. Following a short period of UN administration, the territory was transferred to Indonesia on 1 May 1963. |
| Federation of Rhodesia and Nyasaland | Protectorate of Nyasaland Protectorate of Northern Rhodesia Colony of Southern Rhodesia | 1953 | Yes |
| Afghanistan-Pakistan Confederation | Kingdom of Afghanistan Dominion of Pakistan | 1953–1954 | No | Afghanistan–Pakistan Confederation plan referred to a plan proposed between the governments of Afghanistan and Pakistan between 1953 and 1954 to merge both countries under a single confederation. These plans were started by Ayub Khan, the president of Pakistan and the monarchy of Afghanistan under King Zahir Shah. President Zia-ul-Haq too was for such confederation. "Charles Wilson recalled a map that Zia had also shown to him in which overlay indicated the goal of a confederation embracing first Pakistan and Afghanistan and eventually Central Asia and Kashmir. Zia further explained about the Pakistan-Afghanistan confederation in which Pakistanis and Afghans could travel freely back and forth without passports." General Akhtar Abdur Rahman, considered Zia's right-hand man and more importantly the DG-ISI (1979–1987), himself a Pashtun, "also shared Zia's vision of a post-Soviet "Islamic Confederation" composed of Pakistan, Afghanistan, Kashmir and even the states of Soviet Central Asia." |
| Argentina-Chile Unification | Argentina Chile | 1953 | No | President of Argentina, Juan Domingo Perón, proposed to Chilean presidente, Carlos Ibáñez del Campo, to unify both countries and be the first step for a Hispanoamerican Unification. It was rejected due to Chilean fears of Argentinian absortion, and the fall of Peronist regime in 1955. |
| West Germany | West Germany Saar Protectorate | 1955–1957 | Yes | 1955 Saar Statute referendum. Saarland became a state of Germany and exited France's economic union. |
| United Kingdom | United Kingdom Crown Colony of Malta | 1956 | No | 1956 Maltese United Kingdom integration referendum |
| Ghana | Gold Coast British Togoland | 1956 | Yes | In the 1956 British Togoland status plebiscite 58% of voters supported a union with Ghana, whereas 42% voted in favor of remaining a United Nations Trust Territory under British control until neighbouring French Togoland had decided its future. |
| North Borneo Federation | Crown Colony of North Borneo Crown Colony of Sarawak Protectorate of Brunei | 1956–1960 | No | Sarawak and North Borneo merged with the independent Federation of Malaya several years later, forming Malaysia, while Brunei later became an independent state on its own. |
| United States of Latin Africa | Angola Belgian Congo Ruanda-Urundi French Congo Ubangi-Shari French Chad French Cameroon French Gabon Spanish Guinea São Tomé and Príncipe | 1957–1959 | No | Proposed union of Romance-language-speaking Central African countries envisioned by Barthélemy Boganda. Boganda first called for it in May 1957. The idea's implementation was cut short by Boganda's death in a plane crash on 29 March 1959. Boganda viewed this entity to be a counterweight to the powerful British-influenced southern bloc of South Africa and the Federation of Rhodesia and Nyasaland. |
| Melanesian Federation | Dutch New Guinea Solomon Islands Protectorate Territory of Papua and New Guinea | 1957 | No | Australian Governor General John Kerr was a vocal proponent of the idea of a Melanesian Federation as a solution to the West Papua dispute. |
| Cameroon | Cameroon Spanish Guinea | 1958–1963 | No | The Equatoguinean independence leader Enrique Nvo and the first formal Equatoguinean political party, IPGE, advocated for independence from Spain and a political union between Cameroon and Equatorial Guinea. The idea of a union was deemed unfeasible after the 1963 Spanish Guinean autonomy referendum. |
| Union of African States | Ghana Guinea Mali (joined in 1961) | 1958–1963 | Yes | The union planned to develop a common currency and unified foreign policy amongst members; however, none of these proposals were implemented by the countries. The union was the first organization in Africa to bring together former colonies of the British and the French. Although the union was open to all independent states in Africa, no other states joined. |
| West Indies Federation | British Barbados British Jamaica British Leeward Islands (except the Virgin Islands) British Trinidad and Tobago British Windward Islands Also invited: Crown Colony of the Bahama Islands British Guiana British Honduras British Virgin Islands | 1958 | Yes | The expressed intention of the Federation was to create a political unit that would become independent from Britain as a single state. However, before that could happen, the Federation collapsed due to internal political conflicts. |
| United Arab Republic | Republic of Egypt Syrian Republic | 1958 | Yes | A short-lived Pan-Arab state. |
| United Arab States | United Arab Republic Mutawakkilite Kingdom of Yemen | 1958 | Yes | Loose confederation between the United Arab Republic and North Yemen. |
| Arab Federation | Kingdom of Iraq Hashemite Kingdom of Jordan | 1958 | Yes | An attempt to unify the two Hashemite kingdoms of Iraq and Jordan. While successful, the short-lived union was disestablished after a military coup deposed Faisal II of Iraq. |
| Sahel-Benin Union | Republic of Upper Volta Niger Republic of Dahomey Ivory Coast | 1958 or 1959 ?–1959 | Yes | |
| Mali Federation | Senegal Sudanese republic | 1959–1960 | Yes | Senghor became very wary of unification efforts after the failed experiment and despite attempts to create other federations in West Africa and with Senegal's neighbours, Senghor often restrained these efforts and they only progressed after his rule. In addition, as the first failed unification experiment in Africa, the Mali Federation served as a lesson in future attempts at unification throughout the continent. Keïta became more assertive with pushing his ideology after the collapse of the federation and refused diplomatic relations with Senegal for many years. Nonetheless, Mali under Keïta still pursued the goal of West African unity but did so in a variety of different international connections. |
| Somali Republic | Trust Territory of Somalia State of Somaliland | 1960 | Yes | On 26 June 1960 the former British Somaliland protectorate briefly obtained independence as the State of Somaliland, with the Trust Territory of Somaliland following suit five days later. The following day, on 27 June 1960, the newly convened Somaliland Legislative Assembly approved a bill that would formally allow for the union of the State of Somaliland with the Trust Territory of Somaliland on 1 July 1960. Following the collapse of Barre's government in early 1991, local authorities, led by the SNM, unilaterally declared independence from Somalia on 18 May of the same year and reinstated the borders of the former short-lived independent State of Somaliland. |
| Soviet Union | Soviet Union People's Republic of Bulgaria | 1960 | No | The leader of the People's Republic of Bulgaria, Todor Zhivkov, suggested in the early 1960s that the country should become a union republic, but the offer was rejected. |
| East African Federation | Kenya Colony Tanganyika Territory Uganda Protectorate Sultanate of Zanzibar | 1960–1964 | No | Proposed political union between the four territories (one colony, two protectorates and one League of Nations mandated territory) under British rule in East Africa in the 1960s. Tanganyika proposed to delay its imminent independence in 1960 so that the four territories might achieve independence together as one federation. In 1963 the leaders of all of the territories (some now independent) pledged to work towards a federation by 1964, but ultimately disputes over the nature of the federation and concerns about sharing power led to the collapse of effort to federate. Only Tanganyika and Zanzibar eventually united in 1964. |
| Cameroon | Cameroon British Cameroon | 1961 | Partially (Southern Cameroons) | In the 1961 British Cameroons referendum, the Christian majority in the south of British Cameroon voted to integrate with Cameroon, whereas the Muslim-majority Northern areas voted to integrate with Nigeria. |
| Nigeria | Nigeria British Cameroon | 1961 | Partially (Northern Cameroons) | In the 1961 British Cameroons referendum, the Christian majority in the south of British Cameroon voted to integrate with Cameroon, whereas the Muslim-majority Northern areas voted to integrate with Nigeria. |
| India | India Portuguese State of India | 1961 | Yes | Annexation of Dadra and Nagar Haveli, Annexation of Goa |
| India | India French Settlements in India | 1962 | Yes | Coup d'état of Yanaon |
| Confederation of Himalayan States | Bhutan Nagaland Nepal North-East Frontier Agency Sikkim | 1962 | No | In 1962, the Chinese Government proposed a Confederation of Himalayan States. |
| Federation of the Emirates of the South | Fadhli Audhali Beihan Dhala Lower Yafa Upper Aulaqi Sheikhdom Alawi Aqrabi Dathina Haushabi Lahej Lower Aulaqi Maflahi Shaib Wahidi | 1962 | Yes | The Federation of the Emirates of the South (Arabic: اتحاد إمارات الجنوب العربي‎ Ittiḥād ʾImārāt al-Janūb al-ʿArabiyy) was an organization of states within the British Aden Protectorate in what would become South Yemen. The Federation of six states was inaugurated in the British Colony of Aden on 11 February 1959, and the Federation and Britain signed a “Treaty of Friendship and Protection,” which detailed plans for British financial and military assistance. It subsequently added nine states and, on 4 April 1962, became known as the Federation of South Arabia. This was joined by the Aden Colony on 18 January 1963. |
| Maphilindo | Malaya Indonesia Philippines | 1963 | No | Proposals to create a union of the people of the Malay race and deal with the continued decolonisation of Southeast Asia led to leaders of the three countries signing the Manila Accord on 5 August 1963. However, cooperation quickly broke down following the formation of Malaysia by Malaya and other former British colonies in the region, which was opposed by Indonesia and the Philippines. |
| Malaysia | Federation of Malaya Crown Colony of North Borneo Crown Colony of Sarawak Colony of Singapore Also invited: Brunei | 1963 | Yes | Singapore was expelled from the federation on 9 August 1965, later forming the Republic of Singapore. Brunei Sultan Omar Ali Saifuddien III accepted the idea but rejected after the Brunei revolt. |
| United Republic of Tanzania | Republic of Tanganyika People's Republic of Zanzibar | 1964 | Yes | |
| Australia | Australia Nauru | 1964–1965 | No | In 1963 the Australian Government proposed that the citizens of Nauru, a United Nations trust territory under Australian administration, would move to Curtis Island and become Australian citizens. By that time, Nauru had been extensively mined for phosphate by companies from Australia, Britain and New Zealand damaging the landscape so much that it was thought the island would be uninhabitable by the 1990s. The cost of resettling the Nauruans on Curtis Island was estimated to be £10 million, which included housing and infrastructure and the establishment of pastoral, agricultural, and fishing industries. However, the Nauruan people did not wish to become Australian citizens and wanted to be given sovereignty over Curtis Island to establish themselves as an independent nation, which Australia would not agree to. Nauru rejected the proposal to move to Curtis Island, instead choosing to become an independent nation operating their mines in Nauru. Nauru became self-governing in January 1966, and following a two-year constitutional convention, it became independent in 1968 under founding president Hammer DeRoburt. |
| Territory of the Marianas | Territory of Guam Commonwealth of the Northern Mariana Islands | 1969 | No | 1958 Saipan integration referendum, 1961 Northern Mariana Islands status referendum, 1963 Northern Mariana Islands integration referendum, 1969 Guamanian unification with the Northern Mariana Islands referendum, 1969 Northern Mariana Islands status referendum |
| United Arab Emirates | Abu Dhabi Dubai Sharjah Ajman Umm Al Quwain Fujairah Ras Al Khaimah Also invited: Bahrain Qatar | 1971–1972 | Yes | Six independent emirates formed the United Arab Emirates on 2 December 1971. Ras Al Khaimah later joined the federation. |
| Federation of Arab Republics | Libya Egypt Syria Also invited: Iraq Sudan | 1972–1977 | Yes | An attempt by Muammar Gaddafi to build a Pan-Arab state. |
| Arab Islamic Republic | Libya Tunisia | 1974 | No | Proposed by Muammar Gaddafi. |
| Indochinese Federation | North Vietnam South Vietnam Democratic Kampuchea Laos | 1975 | No | Despite Kampuchea's cooperation with the Vietnamese, the Khmer Rouge leadership feared that the Vietnamese communists were planning to form an Indochinese federation, which would be dominated by Vietnam. In order to pre-empt any attempt by the Vietnamese to dominate them, the Khmer Rouge leadership began, as the Lon Nol government capitulated in 1975, to purge Vietnamese-trained personnel within their own ranks. Then, in May 1975, the newly formed Democratic Kampuchea began attacking Vietnam, beginning with an attack on the Vietnamese island of Phú Quốc. |
| India | India Sikkim | 1975 | Yes | After independence in 1947, joining the new Indian Union was rejected by popular vote. Sikkim grew closer to India over time, becoming a protectorate and later a suzerainty of India. With Indian pressure and support, Sikkim voted to join India in 1975. |
| Republic of Guinea-Cape Verde | Guinea-Bissau Cape Verde | 1975 | No | The African Party for the Independence of Guinea and Cape Verde (PAIGC) advocated for the independence of the colonies of Portuguese Guinea and Portuguese Cape Verde, and governed both countries immediately after independence (1974 for Guinea-Bissau, and 1975 for Cape Verde) with the goal of unifying the two. However, following a 1980 coup in Guinea-Bissau, the Cape Verde branch of the party separated to form the African Party for the Independence of Cape Verde (PAICV), ending plans for a union. |
| Indonesia | Indonesia East Timor | 1975–1976 | Yes | Indonesian invasion of East Timor |
| Vietnam | North Vietnam South Vietnam | 1976 | Yes | Fall of Saigon, Reunification Day |
| Solomon Islands | British Solomon Islands Republic of the North Solomons | 1976 | No | The Interim Provincial Government announced that they would declare independence on 1 September, ahead of Papua New Guinea's own planned independence day of 16 September. On 1 September, they issued the 'Unilateral Declaration of Independence of the Republic of the North Solomons'. They sought international recognition through the United Nations, but were unsuccessful. They also failed in an attempt to unite with the Solomon Islands. |
| Socialist Union of the Horn of Africa | Ethiopia Somalia South Yemen | 1977 | No | In early 1977, Castro brought together the leaders of Somalia, Ethiopia and South Yemen to create a socialist federal state in the region. General Mohamed Nur Galal was the former deputy defense minister of Somalia and the vocal point of Somalia's military contacts with Cuba at that time. He was present at the meeting in Aden in March 1977. |
| Libyan-Syrian Union | Libya Syria | 1980 | No | |
| Democratic Confederal Republic of Koryo | North Korea South Korea | 1980 | No | In accordance with the three principles and the ten point programme, Kim Il Sung elaborated on the proposed state, called Democratic Confederal Republic of Koryo (DFRK), on October 10, 1980, in the Report to the Sixth Congress of the Workers' Party of Korea on the Work of the Central Committee. Kim proposed a confederation between North and South Korea, in which their respective political systems would initially remain. It is described by North Korea as a "...peaceful reunification proposal to found a federal state on the condition that the north and the south recognize and tolerate each other's existing ideologies." It was stated that the DFRK should be a neutral country which does not participate in any political, military alliance or bloc, embracing the whole of the territory and people of the country. |
| Swaziland | Swaziland KaNgwane Also invited: KwaZulu | 1982–1989 | No | An attempt to transfer the bantustan, along with parts of the Zulu homeland KwaZulu, to the neighbouring country of Swaziland in 1982 was never realized. This would have given land-locked Swaziland access to the sea. The deal was negotiated by the governments, but was met by popular opposition in the territory meant to be transferred. The homeland's territory had been claimed by King Sobhuza of Swaziland as part of the Swazi monarchs' traditional realm, and the South African government hoped to use the homeland as a buffer zone against guerrilla infiltration from Mozambique. South Africa responded to the failure of the transfer by temporarily suspending the autonomy of KaNgwane, then restoring it in December 1982 and granting it nominal self-rule in 1984. |
| Senegambia Confederation | Senegal The Gambia | 1982–1989 | Yes | A loose confederation was formed, but ended due to the Gambia's lack of interest in integration. |
| Burkina Faso-Ghana Union | Burkina Faso Ghana | 1983–1987 | No | With the coming to power of Thomas Sankara in Burkina Faso in 1983, relations between Ghana and Burkina became both warm and close. Indeed, Jerry Rawlings and Sankara began discussions about uniting Ghana and Burkina in the manner of the defunct Ghana-Guinea-Mali Union, which Nkrumah had sought unsuccessfully to promote as a foundation for his dream of a unified continental government. |
| Yemen | North Yemen South Yemen | 1990 | Yes | Yemeni unification |
| Germany | West Germany East Germany | 1990 | Yes | German reunification |
| Union of Soviet Sovereign Republics | Russian SFSR Byelorussian SSR Ukrainian SSR Azerbaijan SSR Kazakh SSR Kirghiz SSR Tajik SSR Turkmen SSR Uzbek SSR | 1990–1991 | No | 1991 Soviet Union referendum |
| Windward Union | Dominica Grenada Saint Lucia Saint Vincent and the Grenadines | 1991 | No | On January 14, 1991, the four Caribbean island nations of Dominica, Grenada, Saint Lucia, and Saint Vincent and the Grenadines began an initiative to create a political union encompassing themselves. |
| FR Yugoslavia | SR Serbia Montenegro Bosnia and Herzegovina | 1991 | No | Zulfikarpašić–Karadžić agreement |
| FR Yugoslavia | SR Serbia Montenegro | 1992 | Yes | |
| Balkania | SR Serbia Montenegro Kosova | 1993–2006 | No | Suggested by the Kosovo Albanian politician Adem Demaçi |
| South Africa | South Africa Bophuthatswana Ciskei Transkei Venda | 1994 | Yes | During apartheid the South African Government granted nominal independence to four autonomous bantustans within it. While no external country recognized these states, South Africa strongly promoted their independence and the four mutually recognized each other. As South Africa moved to end apartheid, the African National Congress (ANC) party advocated reintegration of all bantustans, including the nominally independent ones, into a unitary South African state. Resistance to integration by leaders of some bantustans led to violence, such as in the Bisho massacre and the Bophuthatswana crisis. Nonetheless, inhabitants of all four independent bantustans participated in the 1994 South African general election, during which a new constitution came into effect which reintegrated all bantustans into South Africa. |

### 21st century

| Proposed state | Components | Time period | Successful? | Notes |
| Asymmetric Federal Moldavian State | Moldova Transnistria | 2003–2005 | No | The Kozak memorandum, officially Russian Draft Memorandum on the Basic Principles of the State Structure of a United State in Moldova, was a 2003 proposal aimed at a final settlement of relations between Moldova and Transnistria and a solving of the Transnistria conflict. It was seen as an extension of the 1997 Moscow memorandum but was ultimately rejected by Moldovan president Vladimir Voronin. The plan, presented in mid-November 2003 by Russia, was a detailed proposal for a united asymmetric federal Moldavian state. First published in Russian on the website of Transnistria's Ministry of Foreign Affairs, the text was promoted by a Russian politician Dmitry Kozak, a close ally of President Vladimir Putin and one of the key figures in his presidential team. For Transnistria, the memorandum presented an end to the previous Moscow policy, which assumed that the region would have equal status in federation with the rest of the country. According to the memorandum, Russian troops (no more than 2000 strong, without heavy armaments) would remain in Transnistria for the transitional period but not later than 2020. |
| United Republic of Cyprus | Cyprus Northern Cyprus | 2004 | No | A referendum was held in Cyprus on 24 April 2004. The two communities were asked whether they approved of the fifth revision of the United Nations proposal for reuniting the island, which had been divided since 1974. While it was approved by 65% of Turkish Cypriots, it was rejected by 76% of Greek Cypriots. |
| Russian Federation | Russian Federation Transnistria | 2006 | No | Proposed Russian annexation of Transnistria |
| Gran Colombia | Colombia Ecuador Panama Venezuela | 2008 | No | Reunification of Gran Colombia, In 2008, Hugo Chávez, president of Venezuela, announced the proposal of the political restoration of the Gran Colombia, under the Bolivarian revolution. |
| Lucayan Federation | Bahamas Turks and Caicos Islands | 2010 | No | The Lucayan Archipelago (named for the original native Lucayan people), also known as the Bahama Archipelago, is an island group comprising the Commonwealth of The Bahamas and the British Overseas Territory of the Turks and Caicos Islands. The archipelago is in the western North Atlantic Ocean, north of Cuba along with the other Antilles, and east and southeast of Florida. In 2010 the leaders of The Bahamas and the Turks and Caicos Islands discussed the possibility of forming a federation. |
| Peru–Bolivian Confederation | Bolivia Peru | 2011 | No | President Ollanta Humala of Peru proposed Bolivian president Evo Morales to reunite the countries in a confederation. The Cabinets of the two countries have held joint meetings. |
| Gulf Union | Bahrain Kuwait Oman Qatar Saudi Arabia United Arab Emirates | 2011–2012 | No | In 2011, King Abdullah of Saudi Arabia proposed a Gulf Union. |
| Russian Federation | Russian Federation Crimea | 2014 | Yes | Crimea seceded from Ukraine and later conducted a referendum to join the Russian Federation and was later annexed by Russia. The referendum was extremely controversial and most countries continue to recognize Crimea as part of Ukraine. |
| Novorossiya | Mykolaiv Oblast Odesa Oblast Kherson Oblast Crimea | 2005–2008 | No | After the Orange Revolution, Dmitri Trenin of the Carnegie Moscow Center wrote that in 2005 and again in 2008 some quarters in Moscow, that were not entirely academic, discussed the idea of a Russia-friendly buffer state, "Novorossiya", being formed out of Southern Ukraine from the Crimea to Odesa in response to perceived Western penetration into the former Soviet Union. |
| Novorossiya | Donetsk People's Republic Luhansk People's Republic Also planned: Kharkiv Oblast Kherson Oblast Dnipropetrovsk Oblast Mykolaiv Oblast Odesa Oblast Zaporizhzhia Oblast Planned, later removed: Sumy Oblast | 2014–2015 | Partial | Novorossiya (Full name: Federal State of Novorossiya) was a confederation between the two self-declared nations of the Donetsk People's Republic and the Luhansk People's Republic, proclaimed on June 24th, 2015. According to Gubarev the full confederation would include Dnipropetrovsk, Kharkiv, Kherson, Mykolaiv, Odesa, Zaporizhzhia and possibly Sumy (later removed). |
| Levantine Confederation | Syria Jordan Palestine Lebanon Israel | 2014–2021 | No | In 2014, a Lebanese political activist and revolutionary Anis al-Naqqash proposed that the solution to the problems of the Middle East region was the establishment of a confederation that unites the states of the Levant, called ‘West Asian region’ by Naqqash. |
| Malorossiya | Donetsk People's Republic Ukraine | 2017 | No | A project was declared on 18 July 2017 by the Donetsk People's Republic to include all of Ukraine, but the name was changed to "Malorossiya" (Little Russia). The Luhansk People's Republic, however, stated that it would not be taking part in the project. The announcement was widely condemned by nations, including Russia, which pointed to the Minsk agreement. |
| Russian Federation | Russian Federation South Ossetia | 2022 | No | On 30 March 2022, President Anatoly Bibilov suggested a referendum on joining Russia, which was to be held on 17 July 2022; the referendum was cancelled on 30 May 2022. |
| Russian Federation | Russian Federation Donetsk People's Republic Luhansk People's Republic Kherson Oblast Zaporizhzhia Oblast | 2022 | Partial | In late September 2022, Russian-installed officials in some parts of Ukraine organized referendum on annexation of occupied territories of Ukraine. On 27 September, Russian officials of the Central Election Commission in Zaporizhzhia claimed that the referendum passed, with 93.11% of voters in favour of joining the Russian Federation. According to the data provided by the commission, the support for the annexation was 90.01% in the Melitopol Raion, while in its administrative center, Melitopol, it was 96.78%. On 29 September, Russia announced that it would formally annex the four regions Luhansk, Donetsk, Zaporizhzhia and Kherson the next day, on 30 September. The referendums were illegal under international law and most countries continue to recognize as part of Ukraine. |
| Alliance of Sahel States | Burkina Faso Mali Niger Also invited: Guinea | 2023–2024 | Partial | In early 2023, Burkina Faso's prime minister after his visit in Mali suggested that the two countries should form a federation to boost their economic clout and fight against the jihadists in the region. Later in December of the same year, the foreign ministers of Burkina Faso, Mali, and Niger recommended the establishment of a confederation that includes every member of the Alliance of Sahel States. The confederation was established on 6 July 2024. |