Westward Expansions Timeline By YooYoo Sep 25, 1783 United states Sep 25, 1803 Louisiana Purchase Sep 25, 1810 Florida Sep 25, 1813 Florida Sep 25, 1819 East Florida Sep 25, 1842 Webster Ashburton Treaty Sep 25, 1845 Texas Annexation Sep 25, 1846 Oregon Territory Sep 25, 1848 Mexican Cession Sep 25, 1853 Gadsden Purchase.