On this date in 1821, Missouri entered the Union as the 24th state. It was the first one located entirely west of the Mississippi River.
By 1818, the Missouri Territory, part of the Louisiana Purchase of 1803, had gained enough settlers to qualify for statehood. Its settlers, however, had come mostly from the South and expected it would be a slave state. When a Missouri statehood bill came before the House, Rep. James Tallmadge of New York proposed amending the measure to bar bringing slaves into the new state and providing for the ultimate emancipation of all slaves born in Missouri. The House approved that approach in 1819. But the Senate refused to go along.
In early 1820, a bill to admit Maine passed the House. Alabama had come into the Union as a slave state in 1819. With Alabama's admission, there were an equal number of senators from free and slave states in that body. Since Maine would come in as a free state, proponents of admitting Missouri as a slave state argued that equality would be retained at 12 each by pairing the two.
The Senate then voted to bar slavery in the rest of the Louisiana Purchase north of the southern boundary of Missouri ? except in Missouri. Although the House rejected this compromise, conferees agreed that Missourians could adopt a constitution that permitted slavery.
But the House rebelled anew when a drafted state constitution barred bringing any free blacks into Missouri. The territorial legislature backed down and pledged that nothing in its constitution could be interpreted as abridging the rights of U.S. citizens. (Slaves were not citizens.) That deal held until 1854, when the Kansas-Nebraska Act repealed the Missouri Compromise. In 1861, when other slave states seceded to trigger the Civil War, Missouri chose to remain in the Union.
