On August 10, 1821, Missouri entered the Union as the twenty-fourth state. Named after the Native American people who originally inhabited the land, Missouri was acquired by the U.S. as part of the 1803 Louisiana Purchase. At that time, the territory's occupants were mainly French settlers. After the War of 1812, American settlers poured into the region.
In 1818, the Speaker of the House of Representatives presented the first petition of the Territory of Missouri requesting statehood. The question of Missouri's admission as a slave or free state led statesman Henry Clay to devise the Missouri Compromise of 1820, admitting Missouri as a slave state while admitting Maine as a free state, and prohibiting slavery in Louisiana Territory north of the parallel 36º 30', Missouri's southern border.
This resolution proved temporary. Congress passed the Compromise of 1850, a series of laws that amended the Fugitive Slave Act, abolished the slave trade in Washington, D.C., and admitted California to the Union as a free state. The Compromise of 1850 also established territorial governments in Utah and New Mexico, but left the issue of slavery in the new territories to be decided by the local residents. In 1854, the Kansas-Nebraska Act served to abrogate the Missouri Compromise. And in 1857, as a part of the Dred Scott decision, the U.S. Supreme Court declared the compromise unconstitutional by ruling that Congress had no power to bar slavery from a territory, as it had in 1820. Four years later, the slavery debate erupted in civil war.