United States Expanding By brennaa Apr 30, 1803 Lousiana Purchase Jun 18, 1812 The War of 1812 Started Feb 18, 1815 End of the War of 1812 Apr 10, 1820 Missouri Compromise Jan 24, 1848 Gold Rush Started Apr 25, 1848 Start of the Mexican-American War Feb 2, 1849 End of Mexican-American War Jun 13, 1855 Gold Rush Ended