Louisiana Purchase - 1803 - Bought from France to gain the Port of New Orleans
Treaty of Paris - 1783 - After the American Revolution
Original 13 Colonies
Florida - Purchased from Spain in 1819
Annexed into the United States in 1845
Oregon Territory - Acquired from Britain with a treaty -
Mexican Cession - Ceded by Mexico after the U.S-Mexican War
Gadsden Purchase- 1854 - Bought from Mexico for $10 Million to finish Transcontinental Railroad