United States territorial acquisitions

United States territorial acquisitions
Animated image depicting U.S. territorial growth
Census Bureau map depicting territorial acquisitions and dates of statehood, probably created in the 1970s or thereabouts
A government map, probably created in the mid-20th century, that depicts a simplified history of territorial acquisitions within the continental United States
Map of current U.S. states that are direct successor states of the original Thirteen Colonies that declared independence from Great Britain in 1776. Indirect successor states (Maine, West Virginia), the District of Columbia and states that acceded to the union after the American Revolutionary War are not included
National Atlas map (circa 2005) depicting territorial acquisitions.

This is a simplified list of United States territorial acquisitions, beginning with American independence. Note that this list primarily concerns land acquired from other nation-states; the numerous territorial acquisitions from American Indians are not listed here.




The Louisiana Purchase, completed in 1803, was negotiated by Robert Livingston during the presidency of Thomas Jefferson; the territory was acquired from France for $15,000,000 (equivalent to $219 million in present day terms). A small portion of this land was ceded to the United Kingdom in 1818 in exchange for the Red River Basin. More of this land was ceded to Spain in 1819 with the Florida Purchase, but was later reacquired through Texas annexation and Mexican Cession.

West Florida

West Florida was declared by President James Madison to be a U.S. possession in 1810.

Red River

Red River Basin, acquired in 1818 by treaty from the United Kingdom, namely the Anglo-American Convention of 1818.

East Florida

The Adams-Onís Treaty of 1819 with Spain resulted in Spain's cession of East Florida and the Sabine Free State and Spain's surrender of any claims to the Oregon Country. Article III of the treaty, when properly surveyed, resulted in the acquisition of a small part of central Colorado.[1]

Along Canadian border

Webster-Ashburton Treaty of 1842 which finalized the border between United States and Canada (a British colony at the time).


Texas Annexation of 1845: The independent Republic of Texas long sought to join the U.S., despite Mexican claims and the warning by Mexican leader Antonio López de Santa Anna warned that this would be "equivalent to a declaration of war against the Mexican Republic." Congress approved the annexation of Texas on February 28, 1845. On December 29, 1845, Texas became the 28th state. Texas had claimed New Mexico east of the Rio Grande but had only made one unsuccessful attempt to occupy it; New Mexico was only captured by the U.S. Army in August 1846 and then administered separately from Texas. Resistance ended with the Siege of Pueblo de Taos on February 5, 1847. Mexico acknowledged the loss of Texas and New Mexico in the Treaty of Guadalupe Hidalgo, signed February 2, 1848.


Oregon Country, the area of North America west of the Rockies to the Pacific, was jointly controlled by the U.S. and the United Kingdom following the Anglo-American Convention of 1818 until June 15, 1846 when the Oregon Treaty divided the territory at the 49th parallel (see Oregon boundary dispute). The San Juan Islands were claimed and jointly occupied by the U.S. and the U.K. from 1846-1872 due to ambiguities in the treaty (see Northwestern Boundary Dispute). Arbitration led to the sole U.S. possession of the San Juan Islands since 1872.

Mexican Cession

Mexican Cession lands were captured in the Mexican-American War in 1846-48, and ceded by Mexico in the Treaty of Guadalupe Hidalgo, where Mexico agreed to the present Mexico – United States border except for the later Gadsden Purchase. The United States paid $15 million (equivalent to $352 million in present day terms) and agreed to pay claims made by American citizens against Mexico which amounted to more than $3 million (equivalent to $70 million today).

Gadsden Purchase

Gadsden Purchase of 1853, United States purchased a strip of land along the U.S.-Mexico border for $10 million (equivalent to $263 million in present day terms), now in New Mexico and Arizona. This territory was intended for a southern transcontinental railroad.

Since 1848

In 1959, 94% of Hawaii's residents voted to relinquish all land claims (proposition 2) to the United States and become a state.

The overseas expansion of the United States into the Caribbean and the Pacific occurred as a consequence of the Guano Islands Act, the Treaty of Paris which ended the Spanish-American War, the acquisition of American Samoa via the Treaty of Berlin, and the annexation of the Republic of Hawaii at the request of the then president of Hawaii, Sanford Dole. Only the Trust Territory of the Pacific Islands (including the Northern Mariana Islands) was gained after World War I.

In the period between the mid-19th century and the early 20th century, the United States gained a number of overseas islands and territories. The following areas have at one time or another been under the control of the United States of America and have not been fully incorporated into the country as states.

Guano islands

The Guano Islands Act, passed on August 18, 1856, provided for U.S. claims to unoccupied islands containing guano deposits. More than 50 islands were eventually claimed.

Of those remaining unquestionably under U.S. control due to this act alone are Baker Island, Jarvis Island, Howland Island, Kingman Reef, and Johnston Atoll. Baker Island, Howland Island, and Navassa Island were annexed in under its provisions in 1857. Today ownership of Navassa is disputed between the U.S. and Haiti. Johnston Atoll was claimed by the U.S. and Hawaiʻi in 1858; the U.S. claim became undisputed in 1898 after the annexation of Hawaiʻi. Midway Atoll was discovered and claimed in 1859 and formally annexed 1867. Kingman Reef was claimed in 1856 and annexed in 1922. Jarvis Island was claimed in March 1857 and annexed in 1858, abandoned in 1879, and reclaimed in 1935.

An even more complicated case probably unresolved until now seems to be the Serranilla Bank and the Bajo Nuevo Bank. In 1971, the U.S. and Honduras signed a treaty recognizing Honduran sovereignty over the Swan Islands.


Alaska Purchase from the Russian Empire for $7,200,000 (2 cents per acre)[3] on March 30, 1867 (equivalent to $113 million in present day terms), as a vital refueling station for ships trading with Asia. The land went through several administrative changes before becoming an organized territory on May 11, 1912 and the 49th state of the U.S. on January 3, 1959. The name "Alaska" was already introduced in the Russian colonial time, when it was only used for the peninsula and is derived from the Aleut alaxsxaq, meaning "the mainland," or more literally, "the object towards which the action of the sea is directed."[4] It is also known as Alyeska, the "great land", an Aleut word derived from the same root.


The Kingdom of Hawaii was long an independent monarchy in the mid-Pacific Ocean. During the 19th century, the first American missionaries and then business interests began to play major roles in the islands. Most notable were the powerful fruit and sugarcane corporations such as the Big Five, which included Castle & Cooke, Alexander & Baldwin, C. Brewer & Co., Amfac and Theo H. Davies & Co..

In January 1893, a group of American and European businessmen organized and carried out a coup d'état backed by the United States military[5][6] which was successful in deposing Hawaiian Queen Lili'uokalani and overthrowing the monarchical system of government. The stated goal of the conspirators was annexation to the United States, both for geostrategic and economic reasons.[6] Although U.S. President Grover Cleveland strongly disapproved the coup – which had been planned by operatives linked to Cleveland's predecessor President Benjamin Harrison – Euro-American business elites maintained political control as the Republic of Hawaii until 1898, when Hawaii President Sanford Dole was offered and agreed to annexation by the United States. The Hawaiian Islands officially became a territory of the U.S. in 1900. Following 94% voter approval of the Admission of Hawaii Act, on August 21, 1959 the Territory of Hawaii became the state of Hawaii and the 50th state of the United States.

With Hawaiʻi came the Palmyra Atoll which had been annexed by the U.S. in 1859 but later abandoned, then later claimed by Hawaiʻi.

Spanish colonies

Post-Spanish-American War map of "Greater America".

Puerto Rico, Guam, and the Philippines (for which the United States compensated Spain $20 million equivalent to $526 million in present day terms), ceded by Spain after the Spanish-American War in the 1898 Treaty of Paris. Spain relinquished all claim of sovereignty over Cuba, but did not cede it to the United States, so it became a protectorate. All four of these areas were under United States Military Government (USMG) for extended periods. Cuba became an independent nation in 1902, and the Philippines became an independent nation in 1946.

This era also saw the first scattered protests against American imperialism. Noted Americans such as Mark Twain spoke out forcefully against these ventures. Opponents of the war, including Twain and Andrew Carnegie, organized themselves into the American Anti-Imperialist League.

During this same period the American people continued to strongly chastise the European powers for their imperialism. The Second Boer War was especially unpopular in the United States and soured Anglo-American relations. The anti-imperialist press would often draw parallels between America in the Philippines and the British in the Second Boer War.[7]


Under the 1898 Treaty of Paris, Spain relinquished all claim of sovereignty over and title to Cuba, with the island to be occupied by the United States. The United States agreed to assume and discharge the obligations for the protection of life and property so long as such occupation should last. Cuba gained formal independence on 20 May 1902, with the independence leader Tomás Estrada Palma becoming the country's first president. Under the new Cuban constitution, however, the U.S. retained the right to intervene in Cuban affairs and to supervise its finances and foreign relations through the Platt Amendment;[8] this, however, was later overturned as part of Franklin Roosevelt's Good Neighbor Policy.[8] Under the Platt Amendment, Cuba also agreed to lease to the U.S. the naval base at Guantánamo Bay. The naval base occupies land which the United States leased from Cuba in 1903 "... for the time required for the purposes of coaling and naval stations." The two governments later agreed that, "So long as the United States of America shall not abandon the said naval station of Guantanamo or the two Governments shall not agree to a modification of its present limits, the station shall continue to have the territorial area that it now has, with the limits that it has on the date of the signature of the present Treaty."[9][10]

Puerto Rico

On July 25, 1898, during the Spanish–American War, Puerto Rico was invaded by the United States with a landing at Guánica. As an outcome of the war, Jones-Shafroth Act granted all the inhabitants of Puerto Rico U.S. citizenship in 1917. The U.S. granted Puerto Ricans the right to democratically elect their own governor in 1948. In 1950, the Truman Administration allowed for a democratic referendum in Puerto Rico to determine whether Puerto Ricans desired to draft their own local constitution without affecting the unincorporated territory status with the U.S.[11] A local constitution was approved by a Constitutional Convention on February 6, 1952, ratified by the U.S. Congress, approved by President Truman on July 3 of that year, and proclaimed by Gov. Muñoz Marín on July 25, 1952, the anniversary of the 1898 arrival of U.S. troops. Puerto Rico adopted the name of Estado Libre Asociado (literally translated as "Free Associated State"), officially translated into English as Commonwealth, for its body politic.[12][13]


In Guam, settlement by foreign ethnic groups was small at first. After World War II showed the strategic value of the island, construction of a huge military base began along with a large influx of people from other parts of the world. Guam today has a very mixed population of 164,000. The indigenous Chamorros make up 37% of the population. The rest of the population consists mostly of whites and Filipinos, with smaller groups of Chinese, Japanese, Koreans, Micronesians, Vietnamese and Indians. Guam today is almost totally Americanized. The situation is somewhat similar to that in Hawaii, but attempts to change Guam's status as an 'unincorporated' U.S. territory have yet to meet with success.


The Philippine Revolution against Spain began in April 1896, culminating two years later with a proclamation of independence and the establishment of the First Philippine Republic. However, the 1898 Treaty of Paris which ended the Spanish-American war transferred control of the Philippines from Spain to the United States. This agreement was not recognized by the nascent Philippine Government which, on June 2, 1899, proclaimed a Declaration of War against the United States.[14] The Philippine-American War ensued, officially ending in 1902, though hostilities continued until about 1913. The war is often cited as another instance of United States imperialism. While many Filipinos were initially delighted to be rid of the Spanish rule of the Philippines, an insurgent Malolos Republic government formed under Emilio Aguinaldo declared war on the United States and waged an unsuccessful struggle for independence. Aguinaldo was captured and pledged his allegiance to the American government in 1901,[15] and the U.S. unilaterally declared an end to the conflict in 1902. Scattered fighting continued, however, until 1913.

The Philippine Organic Act of 1902 provided for the establishment of a bicameral legislature composed of an upper house consisting of the Philippine Commission (an appointive body having both U.S. and Filipino members) and a popularly elected lower house, the Philippine Assembly. The Philippines became a U.S. colony in the fashion of Europe's New Imperialism, with benevolent colonial practices. English joined Spanish as an official language, and English language education was made compulsory. The Philippine Autonomy Act (Jones Law) of 1916 officially declared the United States commitment to grant independence to the Philippines, "...as soon as a stable government can be established therein."[16] Partial autonomy (commonwealth status) was granted in 1935, preparatory to a planned full independence from the United States in 1946.

Preparation for a fully sovereign state was interrupted by the Japanese occupation of the islands during World War II. The United States suffered a total of 62,514 casualties, including 13,973 deaths in its attempt to liberate the Philippines from Imperial Japanese rule during the hard-fought Philippines campaign from 1944-1945. Full independence came with the recognition of Philippine sovereignty by the U.S. in 1946. The Philippines remained under U.S. or Japanese rule until after World War II. The Filipinos welcomed the American reconquest from Japan in 1944, and the U.S. recognized their political independence in 1946.

Wake Island

Wake Island, annexed in 1899 (the claim is currently disputed by the Marshall Islands).


Germany, the United States, and Britain colonized the Samoan Islands. The nations came into conflict in the Second Samoan Civil War and the nations resolved their issues, establishing American Samoa as per the Treaty of Berlin, 1899. The U.S. took control of its allotted region on June 7, 1900, with the Deed of Cession. Tutuila Island and Aunuu Island were ceded by their chiefs in 1900, then added to American Samoa. Manua was annexed in 1904, then added to American Samoa. Swains Island was annexed in 1925 (occupied since 1856), then added to American Samoa. (The claim is currently disputed by Tokelau, a colonial territory of New Zealand.) American Samoa was under the control of the U.S. Navy from 1900 to 1951. American Samoa was made a formal territory in 1929. From 1951 until 1977, Territorial Governors were appointed by the Secretary of the Interior. Immigration of Americans was never as strong as it was, for instance, in Hawaii; indigenous Samoans make up 89% of the population. The islands have been reluctant to separate from the U.S. in any manner.

Virgin Islands

In 1917, the United States purchased the former Danish colony of St. Croix, St. John and St. Thomas, which is now the U.S. Virgin Islands. The United States purchased these islands because they feared that the islands might be seized as a submarine base during World War I. After a few months of negotiations, a sales price of $25 million (equivalent to $428 million in present day terms) was agreed. A referendum held in late 1916 confirmed the decision to sell by a wide margin. The deal was thus ratified and finalized on January 17, 1917, when the United States and Denmark exchanged their respective treaty ratifications. The U.S. took possession of the islands on March 31, 1917. The territory was renamed the U.S. Virgin Islands.[17] U.S. citizenship was granted to the inhabitants of the islands in 1927.

Trust Territory of the Pacific Islands

The Trust Territory of the Pacific Islands (TTPI) was a United Nations trust territory in Micronesia (western Pacific) administered by the United States from July 18, 1947, comprising the former League of Nations Mandate administered by Japan and taken by the U.S. in 1944. The various island groupings in the Trust Territory were later divided up. The Marshall Islands, and the Federated States of Micronesia achieved independence on October 21, 1986. Palau did so in 1994. All three nations signed Compacts of Free Association with the United States.

Mexican boundary

  • The Boundary Treaty of 1970 transferred 2,702.9 acres (10.938 km2) of Mexican territory to the U.S.. In exchange, the U.S. ceded 2,087.87 acres (8.4493 km2) to Mexico, including the little town of Rio Rico, Texas.

See also


  1. ^ "Treaty Text from the Avalon Project". http://www.yale.edu/lawweb/avalon/diplomacy/spain/sp1819.htm. Retrieved November 7, 2006. 
  2. ^ Covenant, CNMI Law Revision Commission, http://www.cnmilaw.org/covenant.htm, retrieved 2008-05-20 
  3. ^ Student Information, Office of Economic Development, State of Alaska, http://www.dced.state.ak.us/oed/student_info/student.htm, retrieved 2009-01-17 
  4. ^ Ransom, J. Ellis. 1940. Derivation of the Word ‘Alaska’. American Anthropologist n.s., 42: pp. 550-551
  5. ^ Hale, C. (2008) "When Hawaii Had a King", Smithsonian Magazine, February 2008, p. 21.
  6. ^ a b Kinzer, Stephen (2006) America's Century of Regime Change from Hawaii to Iraq
  7. ^ Miller 1984, p. 163 "... Will Show No Mercy Real Warfare Ahead For Filipino Rebels Kitchener Plan Adopted The Administration Weary of Protracted Hostilities.' The reference to Kitchener made eminently clear MacArthur's intent, as the British general's tactics in South Africa had already earned ..."
  8. ^ a b http://www.u-s-history.com/pages/h1646.html
  9. ^ "Agreement Between the United States and Cuba for the Lease of Lands for Coaling and Naval stations". The Avalon project, Yale Law School. February 23, 1903. http://www.yale.edu/lawweb/avalon/diplomacy/cuba/cuba002.htm. Retrieved 2007-06-20. 
  10. ^ "Treaty Between the United States of America and Cuba". The Avalon project, Yale Law School. May 29, 1934. http://www.yale.edu/lawweb/avalon/diplomacy/cuba/cuba001.htm. Retrieved 2007-06-20. 
  11. ^ Act of July 3, 1950, Ch. 446, 64 Stat. 319.
  12. ^ Constitution of the Commonwealth of Puerto Rico - in Spanish (Spanish).
  13. ^ Constitution of the Commonwealth of Puerto Rico - in English (English translation).
  14. ^ Pedro Paterno's Proclamation of War, MSC Schools, Philippines, June 2, 1899, http://www.msc.edu.ph/centennial/pa990602.html, retrieved 2007-10-17 
  15. ^ Aguinaldo's Proclamation of Formal Surrender to the United States, Filipino.biz.ph - Philippine Culture, April 19, 1901, http://filipino.biz.ph/history/ag010419.html, retrieved December 5, 2009 
  16. ^ (– Scholar search) Philippine Autonomy Act (Jones Law), Corpus Juris, August 28, 1916, http://www.thecorpusjuris.com/laws/constitutions/9-others/72-philippine-autonomy-act-jones-law.html, retrieved 2008-07-07 [dead link]
  17. ^ Today in History: March 31 : Virgin Islands, U.S. Library of Congress, http://memory.loc.gov/ammem/today/mar31.html, retrieved 2009-12-04 


  • Stephen A. Flanders. Dictionary of American Foreign Affairs (1992)
  • Glenn P. Hastedt, Encyclopedia of American Foreign Policy (2004)
  • Miller, Stuart Creighton (1984), Benevolent Assimilation: The American Conquest of the Philippines, 1899-1903, Yale University Press, ISBN 0300030819 
  • Mellander, Gustavo A.; Nelly Maldonado Mellander (1999). Charles Edward Magoon: The Panama Years. Río Piedras, Puerto Rico: Editorial Plaza Mayor. ISBN 1563281554. OCLC 42970390.
  • Mellander, Gustavo A. (1971). The United States in Panamanian Politics: The Intriguing Formative Years. Danville, Ill.: Interstate Publishers. OCLC 138568.

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