Missouri Compromise, 1820–21, measures passed by the U.S. Congress to end the first of a series of crises concerning the extension of slavery.

By 1818, Missouri Territory had gained sufficient population to warrant its admission into the Union as a state. Its settlers came largely from the South, and it was expected that Missouri would be a slave state. To a statehood bill brought before the House of Representatives, James Tallmadge of New York proposed an amendment that would forbid importation of slaves and would bring about the ultimate emancipation of all slaves born in Missouri. This amendment passed the House (Feb., 1819), but not the Senate. The bitterness of the debates sharply emphasized the sectional division of the United States.

In Jan., 1820, a bill to admit Maine as a state passed the House. The admission of Alabama as a slave state in 1819 had brought the slave states and free states to equal representation in the Senate, and it was seen that by pairing Maine (certain to be a free state) and Missouri, this equality would be maintained. The two bills were joined as one in the Senate, with the clause forbidding slavery in Missouri replaced by a measure prohibiting slavery in the remainder of the Louisiana Purchase north of 36°30'N lat. (the southern boundary of Missouri). The House rejected this compromise bill, but after a conference committee of members of both houses was appointed, the bills were treated separately, and in Mar., 1820, Maine was made a state and Missouri was authorized to adopt a constitution having no restrictions on slavery.

A provision in the Missouri constitution barring the immigration of free blacks to the state was objectionable to many Northern Congressmen, and necessitated another congressional compromise. Not until the Missouri legislature pledged that nothing in its constitution would be interpreted to abridge the rights of citizens of the United States was the charter approved and Missouri admitted to the Union (Aug., 1821). Henry Clay Clay, Henry, 1777–1852, American statesman, b. Hanover co., Va.

Early Career

His father died when he was four years old, and Clay's formal schooling was limited to three years.
..... Click the link for more information. , as speaker of the House, did much to secure passage of the compromise—so much, in fact, that he is generally regarded as its author, even though Senator Jesse B. Thomas of Illinois was far more responsible for the first bill. The 36°30' proviso held until 1854, when the Kansas-Nebraska Act Kansas-Nebraska Act, bill that became law on May 30, 1854, by which the U.S. Congress established the territories of Kansas and Nebraska. By 1854 the organization of the vast Platte and Kansas river countries W of Iowa and Missouri was overdue.
..... Click the link for more information. repealed the Missouri Compromise.

Bibliography

See studies by G. Moore (1953, repr. 1967) and R. H. Brown (1964).

Missouri Compromise

(1820) Act passed by the U.S. Congress admitting Missouri to the Union as the 24th state. After the territory requested statehood without slavery restrictions, Northern congressmen tried unsuccessfully to attach amendments restricting further slaveholding. When Maine (originally part of Massachusetts) requested statehood, a compromise led by Henry Clay allowed Missouri admission as a slave state and Maine as a free state, with slavery prohibited from then on in territories north of Missouri's southern border. Clay's compromise appeared to settle the slavery-extension issue but highlighted the sectional division.