List of proposed state mergers

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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.


Until the 15th century[edit]

Proposed state Components Time period Successful? Notes
Angevin Union Kingdom of Hungary
Kingdom of Poland (1025–1385)
1370 Yes
See Union of Hungary and Poland
Jagiellonian Union Kingdom of Hungary
Kingdom of Poland (1385–1569)
1440 Yes
See Union of Hungary and Poland

Early modern period[edit]

Proposed state Components Time period Successful? Notes
Polish–Lithuanian Commonwealth Kingdom of Poland (1385–1569)
Grand Duchy of Lithuania
1569 Yes
See Union of Lublin
Polish–Lithuanian–Muscovite Commonwealth Polish–Lithuanian Commonwealth
Tsardom of Russia
1574–1658 No
Estandarte Real de Felipe II.svg Iberian Union Coat of arms of Portugal (1640).svg Crown of Portugal
Coat of Arms of the Crown of Castile (16th Century-1715).svg Crown of Castille
Escudo de Aragón-Sicilia.svg Crown of Aragon
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.
Coat of arms of the January Uprising.svg Polish–Lithuanian–Ruthenian Commonwealth Polish–Lithuanian Commonwealth
Cossack Hetmanate
1658–1659 No Treaty of Hadiach
Kingdom of Great Britain  Kingdom of England
 Kingdom of Scotland
1707 Yes Though having been ruled since 1603 in Personal Union when James VI succeeded both the English and Scottish crowns both countries remained separate sovereign nations states until 1706 when the Treaty of Union unified them into a single entity.
United States of America Vermont Republic
United States of America
1777–1791 Yes
United States of America  Connecticut
 New Hampshire
 New Jersey
 New York
 North Carolina
 Rhode Island
 South Carolina
1786-1788 Yes
United States Constitution is ratified by the Thirteen Original Colonies, replacing the Articles of Confederation and thereby forming a Federal government, ending the individual sovereignty of the US States.

19th century[edit]

Proposed state Components Time period Successful? Notes
United Kingdom of Great Britain and Ireland  Kingdom of Great Britain
 Kingdom of Ireland
1800 Yes
Most of Ireland left the union as the Irish Free State in 1922.
Gran Colombia United Provinces of New Granada
Free Province of Guayaquil
1819–1830 Yes
First Mexican Empire Mexico
Captaincy General of Guatemala
1821 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 was not recognized by the pro-independence provinces.

Federal Republic of Central America El Salvador
Los Altos
Costa Rica
1823 Yes
Costa Rica Costa Rica
1824 Yes The old "Partido de Nicoya" currently encompasses most of the 21st-century Guanacaste Province. See Annexation of Nicoya.
Peru–Bolivian Confederation Bolivia
1829–1839 Yes
United States of America United States of America
Republic of Texas
1845 Yes Texas annexation
Kingdom of Italy Kingdom of Sardinia
Papal States
Grand Duchy of Tuscany
Duchy of Parma
Duchy of Modena and Reggio
Kingdom of the Two Sicilies
Kingdom of Lombardy–Venetia (Part of Austrian Empire)
1848–1870 Yes Although the Kingdom of Italy was proclaimed in 1861, the Italian Unification is generally considered to have been incomplete until after the integration of Venetia in 1866 and the capture of Rome in 1870. See Italian Unification and Expedition of the Thousand.
Federation of Central America El Salvador
1852 Yes Second attempt at unification that lasted for less than a month.
Liberia Liberia
Republic of Maryland
1854-1857 Yes Republic of Maryland was officially named Maryland in Liberia during its independence referendum on May 29, 1854.
Confederate States of America South Carolina
North Carolina
1861 Yes
American Civil War
United Principalities Wallachia
1862 Yes Becomes Kingdom of Romania in 1881.
Kingdom of Greece Kingdom of Greece
United States of the Ionian Islands
1864 Yes Treaty of London (1864)
North German Confederation  Kingdom of Prussia
 Kingdom of Saxony
 Grand Duchy of Hesse
 Grand Duchy of Mecklenburg-Strelitz
 Grand Duchy of Oldenburg
 Duchy of Saxe-Weimar-Eisenach
 Duchy of Anhalt
 Duchy of Brunswick
 Duchy of Saxe-Altenburg
 Duchy of 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.
Canada Province of Canada
 New Brunswick
 Nova Scotia
1867 Yes Canadian Confederation
Antillean Confederation Captaincy General of Cuba
Captaincy General of Puerto Rico
 Dominican Republic
1869–1870 No Proposed by Ramón Emeterio Betances.
German Empire North German Confederation
Kingdom of Bavaria
Kingdom of Württemberg
Grand Duchy of Baden
Grand Duchy of Hesse
Austrian Empire
1871 Partial
Unification of Germany (excluding Austria) after German victory over the French in the Franco-Prussian War. See also, the German Question regarding the competing ideas of "Greater Germany" and "Lesser Germany" (whether or not a united Germany should include the Austrian Empire). The matter was settled with the Austro-Prussian War in 1866, in which Prussia assumed leadership of the various minor German nation states.
Principality of Bulgaria Bulgaria
East Rumelia
1885-1886 Yes After Bulgaria crushed 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.
Greater Republic of Central America El Salvador
Considered joining:
Costa Rica
1895–1898 Yes
United States of America United States of America
Republic of Hawaii
1898 Yes United States annexation of the Territory of Hawaii

20th century[edit]

Proposed state Components Time period Successful? Notes
 Australia  New South Wales
South Australia
 Western Australia
Also invited:
 New Zealand
1901 Yes Federation of Australia
 Union of South Africa  Cape Colony Colony of Natal

 Orange River Colony

 Transvaal Colony

1909 Yes Union of South Africa
Balkan Socialist Federation  Principality of Albania
 Kingdom of Bulgaria
 Kingdom of Yugoslavia
1910–1916 No
Kingdom of Yugoslavia Kingdom of Montenegro
Kingdom of Serbia
State of Slovenes, Croats and Serbs
1918 Yes
Creation of Yugoslavia
Kingdom of Romania  Kingdom of Romania
Moldavian Democratic Republic
1918 Yes
See Union of Bessarabia with Romania, Treaty of Bucharest
Kingdom of Romania  Kingdom of Romania
Banat Republic (Eastern part)
Duchy of Bukovina
1918 Yes
Unification of Greater Romania
Międzymorze  Belarusian People's Republic
 Czechoslovak Republic
Hungarian People's Republic
 Polish Republic
 Kingdom of Romania
 Ukrainian People's Republic
 Kingdom of Yugoslavia
 Kingdom of Bulgaria
November or December 1918 No Also called "Intermarium". Suggested shortly after World War I to combat the influences of Germany and Russia.
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 Empire 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.
 Kingdom of Romania  Kingdom of Romania
Kingdom of Hungary
1919 No Federation between the Kingdom of Romania and the Kingdom of Hungary in personal union under the Romanian King, proposed by the Hungarian statesman István Bethlen.[1][2]
Ukrainian People's Republic Ukrainian People's Republic
West Ukrainian People's Republic
1919 Yes
Act Zluky
Soviet Union Byelorussian SSR
Russian SFSR
Transcaucasian SFSR
Ukrainian SSR
1922 Yes
Treaty on the Creation of the USSR
Nazi Germany Nazi Germany
Federal State of Austria
1938 Yes
 Republic of Turkey  Republic of Turkey
 Hatay State
1939 Yes Hatay was a disputed territory between Syria and Turkey until 2004. Territory ceded from Syria to Turkey during the French Mandate of Syria, never formally recognized by Syria, but gave it up in 2004.
Polish-Czechoslovak confederation  Czechoslovak Republic
 Polish 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
Socialist Federal Republic of Yugoslavia 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 getting Albania into accepting 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
1947–1948 Yes Annexation of Junagadh
 India  India
Princely states
1947–1950 Yes Instrument of Accession
 Pakistan  Pakistan
Princely states
1947–1950 Yes Instrument of Accession
 India  India
1948 Yes Annexation of Hyderabad
Canada Canada
1949 Yes Newfoundland Act
Federation of Rhodesia and Nyasaland  Nyasaland
 Northern Rhodesia
 Southern Rhodesia
1953 Yes
A semi-independent state.
United Kingdom United Kingdom  United Kingdom
Crown Colony of Malta
1956 No See 1956 Maltese United Kingdom integration referendum.
North Borneo Federation North Borneo
 Protectorate of Brunei
1956–1960 No Sarawak and North Borneo (now known as Sabah) joined the Federation of Malaya several years later, a predecessor to modern Malaysia, while Brunei reformed into an independent monarchy.
United Arab States  United Arab Republic
 Mutawakkilite Kingdom of Yemen
1958 Yes
Loose confederation between the United Arab Republic and (North) Yemen.
 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.
Arab Federation  Kingdom of Iraq
1958 Yes
(14 February – 2 August 1958)
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 King Faisal II of Iraq.
Somali Republic Somalia
1960 Yes
On June 26, 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.[3][4] The following day, on June 27, 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 July 1, 1960.[5] 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.
East African Federation Kenya
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 in order 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.
Malaysia  Malaya
North Borneo
Also invited:
1963 Yes Singapore was expelled from the federation on 9 August 1965 due to political conflict and power tension.
 Tanzania  Tanganyika
1964 Yes
 United Arab Emirates  Abu Dhabi
Dubai Dubai
Umm al-Qaiwain
 Ras Al Khaimah
Also invited:
1971 Yes Six independent emirates formed the United Arab Emirates on December 2, 1971. Ras Al Khaimah later joined the federation.
Arab Islamic Republic  Libya
1974 No Proposed by Muammar Gaddafi.
 India  India
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[citation needed] of India. With Indian pressure and support, Sikkim voted to join India in 1975.[6][7]
 Vietnam  North Vietnam
 South Vietnam
1976 Yes Unified due to military conquest. See Reunification Day and the Fall of Saigon.
Egypt Federation of Arab Republics  Libya
Also invited:
1972–1977 Yes
An attempt by Muammar Gaddafi to build a Pan-Arab state.
Senegambia Confederation  The Gambia
1982–1989 Yes
A loose confederation was formed, but ended due to the Gambia's lack of interest in integration.
 Yemen  North Yemen
 South Yemen
1990 Yes Yemeni unification
 Germany  East Germany
 West Germany
1990 Yes German reunification
Union of Sovereign States  Russian SFSR
 Ukrainian SSR
 Byelorussian SSR
 Azerbaijan SSR
 Kazakh SSR
 Kirghiz SSR
 Tajik SSR
 Turkmen SSR
 Uzbek SSR
1990–1991 No An attempt by Mikhail Gorbachev to avert the collapse of the Soviet Union and reorganize the union into a new confederated entity.
 FR Yugoslavia  SR Serbia
 Bosnia and Herzegovina
1991 No Zulfikarpašić–Karadžić agreement

21st century[edit]

Proposed state Components Time period Successful? Notes
United Republic of Cyprus  Republic of Cyprus
 Turkish Republic of Northern Cyprus
2004 No A referendum was held in Cyprus on 24 April 2004.[8] 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.[9]
Peru–Bolivian Confederation  Bolivia
2011 No President Ollanta Humala of Peru proposed Bolivian president Evo Morales to reunite the countries in a confederation.[10][11] The Cabinets of the two countries have held joint meetings.[12]
 Russia  Russia
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 controversial and most countries continue to recognize Crimea as part of Ukraine.
Romania Unified Romania  Romania
2018 No Unification of Romania and Moldova has been proposed since 1991, supported by a minority according to polls, but Moldovan PM Pavel Filip ruled out reunification with Romania, despite growing calls from Moldovans for unification.[13] Unification was supported by the Romanian government. See also Greater Romania.


Proposed state Components First proposed Notes
United States United States  Greenland
 United States
1867 The idea for the United States to buy Greenland was first proposed during the administration of Andrew Johnson, when, in 1867, Secretary of State William H. Seward unsuccessfully proposed buying Greenland and Iceland from the Danish Kingdom. A post-World War II bid was also declined by Denmark.[14] In 2018 and 2019, Donald Trump spoke to aides about acquiring the island, a proposal that was ridiculed; Greenlandic and Danish officials firmly rebuffed the suggestion that the island could be sold.[15][16]
United Ireland  Republic of Ireland
Northern Ireland Northern Ireland
1921 A United Ireland has been proposed since the Partition of Ireland (1921) and is supported by the main political parties in the Republic of Ireland, and by two of the four main parties in Northern Ireland. See also Unionism in Ireland and Nationalism in Ireland.
Korea Unified Korea  North Korea
 South Korea
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 the unification be done under one sociopolitical system while abandoning the other, similarly to German reunification.[17]
Unified China  China
1979 Unification of the territories of China and Taiwan is the nominal goal of both governments, who both operate under the One-China policy.
Union State  Belarus
1999 Russia and Belarus signed an agreement to form the Union State in 1999, aiming to continue deeper integration, possibly until unification.[18][19]
 East African Federation  Burundi
 South Sudan
2004 Proposed political union between the six member states of the East African Community.[20] Federation was proposed in 2004, but in 2016 it was decided that confederation would be the short-term goal. South Sudan is not as integrated as the other five members, having only gained independence from Sudan in 2011.[21]
Albania Unified Albania  Albania
2008 Since the majority ethnic-Albanian Kosovo declared independence in 2008, the potential unification with Albania has emerged as an idea, although it is opposed by much of the international community.[22]

See also[edit]


  1. ^ Ignác Romsics, Social Science Monographs, 1995, István Bethlen: a great conservative statesman of Hungary, 1874-1946, p. 111
  2. ^ Béla K. Király, Gunther Erich Rothenberg, War and Society in East Central Europe: Trianon and East Central Europe antecedents and repercussions, p. 114
  3. ^ "Somalia".
  4. ^ Encyclopædia Britannica, The New Encyclopædia Britannica, (Encyclopædia Britannica: 2002), p.835
  5. ^ "Archived copy". Archived from the original on 28 September 2011. Retrieved 25 January 2011.CS1 maint: archived copy as title (link)
  6. ^ "The Forgotten Kingdom". FP. Retrieved 27 August 2016.
  7. ^ "25 years after SIKKIM". Nepali Times. 23 March 2001. Retrieved 27 August 2016.
  8. ^ Election profile IFES Election Guide
  9. ^ "What do the results of the referendum in Cyprus show?". Retrieved 29 September 2011.
  10. ^ "Humala Invites Morales to Consider the Re-Unification of Peru and Bolivia". MercoPress. 22 June 2011. Retrieved 25 May 2016.
  11. ^ "Humala Says Dreams of Peru-Bolivia Reunification". Buenos Aires Herald. 22 June 2011. Retrieved 25 May 2016.
  12. ^ "Peru and Bolivia reach gas deal at 'bi-national cabinet'". 24 June 2015. Retrieved 22 July 2016.
  13. ^ Rankin, Jennifer (11 May 2018). "Moldova PM rules out reunification with Romania" – via
  14. ^ Paul Musgrave (16 August 2019). "American Imperialists Have Always Dreamed of Greenland". Foreign Policy.
  15. ^ Peter Baker & Maggie Haberman (21 August 2019). "Trump's Interest in Buying Greenland Seemed Like a Joke. Then It Got Ugly". New York Times.
  16. ^ Katie Rogers (16 August 2019). "Eyeing Greenland, Trump Again Mixes Real Estate With Diplomacy". New York Times.
  17. ^ Babones, Salvatore (17 October 2014). "2015: The Year of Korean Reunification?". The National Interest. Retrieved 2 August 2015.
  18. ^ Brennan, David (16 February 2019). "Russia May Absorb Belarus: 'We're Ready to Unite,' President Says". Newsweek. Retrieved 10 April 2019.
  19. ^ Snegovaya, Maria (4 April 2019). "Russia Is Eyeing Belarus—and It Might Spark a Conflict With the West Far Sooner Than Ukraine". Newsweek. Retrieved 10 April 2019.
  20. ^ LAMU (3 September 2009). "An East African Federation: Big ambitions, big question-marks". The Economist. Retrieved 2 August 2015.
  21. ^ "East African Nations agree to disagree". All Africa. 30 November 2016. Retrieved 20 December 2016.
  22. ^ Bytyci, Fatos; Robinson, Matt (7 April 2015). "Albania and Kosovo to unite, inside EU or not: Albanian PM". Reuters. Retrieved 10 April 2019.