1783
 Former 13 coloniesTreaty of Paris of 1783 following American Revolutionary War1803
 Louisiana PurchasePurchased from France for $15 million, including assumed claims1819Florida (East and West)Purchased from Spain for $5 million in assumed claims under Adams-OnĂs Treaty1845TexasAnnexation of independent republic1846Oregon TerritoryThe Oregon Treaty with Great Britain1848Mexican CessionPurchase from Mexico following American-Mexican War; $15 million plus 3.25 million in assumed claims1853Gadsden PurchasePurchased from Mexico for $10 million1857Baker Island
Howland IslandUnincorporated territory claimed under Guano Act of 1856; under the jurisdiction of the U.S. Fish and Wildlife Service1857Navassa IslandUnincorporated territory claimed under Guano Act of 1856; under the jurisdiction of the U.S. Fish and Wildlife Service1858Jarvis IslandUnincorporated territory claimed under Guano Act of 1856; under the jurisdiction of the U.S. Fish and Wildlife Service1858Johnston AtollUnincorporated territory annexed under Guano Act of 1856; under the jurisdiction of the U.S. Fish and Wildlife Service1867AlaskaPurchased from Russia for $7.2 million; Statehood 19591867Midway IslandsUnincorporated territory claimed under Guano Act of 1856; under the jurisdiction of the U.S. Fish and Wildlife Service1898Hawaiian IslandsAnnexation of independent republic; Statehood 19591898Palmyra AtollAcquired with Hawaii; under the jurisdiction of the U.S. Fish and Wildlife Service1898Philippine IslandsPurchased from Spain for $20 millon following Spanish-America War; fully independent in 19461898Puerto RicoAnnexed following Spanish-America War; currently a self-governing commonwealth of the United States1898GuamAnnexed following Spanish-America War; in 1950 became organized, unincorporated U.S. territory under jurisdiction of Office of Insular Affairs of the Department of the Interior1899American SamoaAnnexed in settlement with Britain and Germany; currently an unorganized, unincorporated U.S. territory under jurisdiction of Office of Insular Affairs of the Department of the Interior1899Wake IslandAnnexation of unoccupied area1903
Panama Canal ZoneLeased from Panama for $10 million, plus $250,000 annually; ceded to Panama in 19991917U.S. Virgin IslandsPurchased from Denmark for $25 million; currently an organized, unincorporated U.S. territory1922Kingman ReefAnnexed 1922; later airline refueling; currently uninhabited; National Wildlife Refuge1947Northern Mariana IslandsUnited Nations Trust Territory; in 1986 became a self-governing U.S. commomwealth1947The Federated States of MicronesiaUnited Nations Trust Territory; 1986 became a sovereign, self-governing republic1947Republic of PalauUnited Nations Trust Territory; in 1994 became a sovereign, self-governing republic1947
 Republic of the Marshall IslandsUnited Nations Trust Territory; in 1986 became a sovereign, self-governing republic
