US Imperialism By akoop 1803 Jefferson does the Louisianna purchase 1812 War of 1812 1818 US and Britain have joint custody of Oregon 1819 Spain cedes Florida to the US 1823 Monroe Doctrine is put in place 1845 Texas joins the US 1846 US gains Oregon at the 49th parallel 1846 Mexican American War 1848 Mexican Cession gives US from Texas to CA Jul 8, 1853 Commodore Perry opens Japan Edo Bay, Japan 1854 Perry returns to negotiate a treaty 1858 Japan is officially open to trade with US 1867 US purchases Alaska 1867 US claims the Midway Islands 1870 US gains access to Samoa 1899 Britain pulls out of Samoa and its just Ger. and US