History of Congress By courtneyamundson Jun 1, 1800 Capital settled at the Potomac River Period: Jun 1, 1800 to Dec 7, 1941 History of Congress Nov 4, 1811 Henry Clay elected as Speaker of House Jun 1, 1812 U.S. declared war for the first time Jan 1, 1819 Capital was rebuilt Jan 1, 1820 Congress passed the Missouri Compromise Jan 1, 1850 21,551 post offices were built Jan 1, 1850 Compromise of 1850 held the Union together for 10 more years Nov 1, 1860 Abraham Lincoln elected Dec 1, 1860 South Carolina left the Union Apr 12, 1861 Civil War begins Dec 2, 1863 Dome on the Capital was finished Jan 1, 1865 Congress passed amendment abolishing slavery Jan 1, 1897 Hawaii annexed Dec 7, 1941 Pearl Harbor