Westward Expansion of the United States 1783–1898

British recognition of American independence by the Treaty of Paris (1783) dissolved the 1763 Line of Proclamation and effectively doubled the territory of the new republic from its original Thirteen Colonies. A further doubling occurred with the Louisiana Purchase from Napoleonic France (1803), which extended the western boundary to the Mississippi River. The next overburdened colonial power in American sights was Spain, which surrendered Florida by the Adams-Onìs Treaty (1819). Within months of the Treaty taking effect, Mexico was independent, and next in the firing line for American aggrandizement. The annexation of Texas (1845) provoked the Mexican-American War (1845–48). Overwhelming victory resulted in the cession of a broad corridor to the Pacific at Guadaloupe-Hidalgo, topped off by the Gadsden Purchase (1853). To the north, the Red River basin and Oregon Country (a condominium) were negotiated with Britain (1818 and 1846). Alaska was purchased from Russia (1867), and Hawaii annexed in 1898.