Missouri Compromise

In US history, the solution by Congress (1820–21) of a sectional crisis caused by the request from Missouri for admission to the Union as a slave state, despite its proximity to existing nonslave states. The compromise was the admission of Maine as a nonslave state to keep the same ratio. In addition, slavery was forbidden in the other areas of the Louisiana Purchase north of latitude 36° 30' N.

The Missouri territory, which permitted slaves, applied for statehood in 1819. At the time there were an equal number of slave and free states in the Union. Representative James Tallmadge of New York tried to pass an amendment that would prohibit further introduction of slaves in Missouri and the freeing of present slaves when they reached the age of 25. The Tallmadge Amendment passed in the House of Representatives, but was defeated in the Senate, and a bitter debate, reflecting many of the moral and legal issues of slavery, followed.

The issue was resolved, largely through the efforts of Henry Clay, when Maine requested admission into the Union. Missouri was admitted as a slave state without the restrictions of the Tallmadge Amendment, and Maine was accepted as a free state. A Second Missouri Compromise, passed in 1821, forbade Missouri's new legislature from denying free blacks their constitutional rights. Missouri became the 24th state on 10 August, 1821.

The debate over the admission of Missouri into the Union brought the issue of slavery into the centre of US politics for the first time. The compromise temporarily resolved the sectional crisis, until the Kansas-Nebraska Act repealed it in 1854. See also United States: history 1783–1861, Monroe and territorial expansion.