United States territorial acquisitions table
Following are the historical territorial acquisitions of the United States:
| Accession | Date | Area (sq.mi.) | Area (km2.) | Cost in dollars |
|---|---|---|---|---|
| Original territory of the Thirteen States (western lands, roughly between the Mississippi River and Appalachian Mountains, were claimed but not administered by the states and were all ceded to the federal government or new states by 1802) | 1783 | 892,135 | 2,310,619 | ----- |
| Annexation of the Vermont Republic | 1791 | 9,616 | 24,905 | ----- |
| Louisiana Purchase, from France | 1803 | 827,987 | 2,144,476 | $15,000,000 |
| Florida Parishes, annexed from the Republic of West Florida, which took it from Spain in a filibusting expedition in 1810 | 1810 | 4,685.184 | 12,134.57 | ----- |
| Florida (East and West), purchased from Spain | 1819 | 72,101 | 186,740 | $5,000,000 |
| Texas annexation | 1845 | 389,166 | 1,007,935 | ----- |
| Oregon Territory, by treaty with Great Britain | 1846 | 286,541 | 742,137 | ----- |
| Mexican Cession, from Mexico | 1848 | 529,189 | 1,370,593 | $15,000,000 |
| Gadsden Purchase, from Mexico | 1854 | 29,670 | 76,845 | $10,000,000 |
| Baker Island, unincorporated territory claimed under Guano Act of 1856 | 1857 | 0.5 | 1.29 | ----- |
| Howland Island, unincorporated territory claimed under Guano Act of 1856 | 1857 | 0.6 | 1.55 | ----- |
| Jarvis Island, unincorporated territory claimed under Guano Act of 1856 | 1857 | 1.7 | 4.4 | ----- |
| Johnston Atoll, unincorporated territory claimed under Guano Act of 1856 | 1857 | 1.1 | 2.85 | ----- |
| Alaska Purchase, from Russia | 1867 | 591,000 | 1,723,336 | $7,200,000 |
| Midway Islands, annexation of unoccupied area | 1867 | 2 | 5.18 | ----- |
| Annexation of the Republic of Hawaii | 1898 | 6,450 | 16,705 | ----- |
| Philippines, purchased from Spain (Full independence was granted in July, 1946) | 1898 | 115,800 | 299,921 | $20,000,000 |
| Puerto Rico, by treaty with Spain | 1898 | 3,508 | 9,085 | ----- |
| Guam, by treaty with Spain | 1899 | 209 | 541 | ----- |
| Eastern Samoa, by treaty with Great Britain and Germany | 1899 | 76 | 197 | ----- |
| Panama Canal Zone, by treaty with Panama | 1903 | 553 | 1,432 | $10,000,000 (plus $250,000 annually) |
| Guantánamo, by treaty with Cuba | 1903 | 45 | 116.5 | $3,386.25 (rent annually) |
| Annexation of the Indian Territory | 1906 | 31,069 | 80,468 | ----- |
| Danish Virgin Islands (excluding Water Island), by purchase from Denmark | 1917 | 136 | 352 | $25,000,000 |
| Kingman Reef, annexed | 1922 | 0.4 | 1.0 | ----- |
| Swains Island, annexed | 1925 | 0.94 | 2.43 | ----- |
| Kanton Island and Enderbury Island, joint occupation with Britain (Independent as Republic of Kiribati in 1979) | 1938 | 6.5 | 16.8 | ----- |
| Water Island, by purchase from the East Asiatic Company, a private shipping company based in Denmark (which at the time was under German occupation) | 1944 | 0.8 | 2.0 | $10,000 |
| Mariana Islands, United Nations Trust Territory; self-governing as Northern Mariana Islands | 1947 | 179 | 467 | ----- |
| Caroline Islands, United Nations Trust Territory; 1986 most islands adopt commonwealth status as Federated States of Micronesia | 1947 | 500 | 1,295 | ----- |
| Marshall Islands, United Nations Trust Territory; 1979 self-governing; 1986 independent as Republic of the Marshall Islands | 1947 | 70 | 181 | ----- |
For information on internal territorial acquisitions, see List of U.S.–Native American treaties.