Westward Expansion By deepp4 Period: Mar 31, 1780 to Mar 31, 1850 U.S. Expansion Jul 4, 1783 United States The United States fought the British and won 13 colonies. Apr 30, 1803 Louisiana Purchase Nov 22, 1820 Missouri Compromise of 1820 May 20, 1830 Indian Removal Act Jul 21, 1845 Annexation of Texas Apr 12, 1846 Oregon Feb 12, 1848 Mexican Cession May 24, 1849 Californian Gold Rush Oct 30, 1853 Gadsen Purchase