In U.S. history, the Missouri Compromise was worked out between the North and the South, and passed by the U.S. Congress to allow Missouri to be admitted as the 24th state of the Union. The territory of Missouri first applied for statehood in 1817, and as early as 1819, Congress was considering legislation that would allow Missouri to frame a state constitution.

However, when Representative James Tallmadge of New York attempted to add an anti-slavery amendment to the bill, an ugly debate broke out over slavery and the government's right to restrict slavery. The Tallmadge amendment prohibited any additional slaves into Missouri and provided for emancipation of those already there when they reached age 25.

The amendment passed the House of Representatives, which was, at the time, controlled by the more populous North. When the bill reached the Senate however, it failed, since the Senate was equally divided between free and slave states. As it would turn out, the cowards in Congress adjourned before ever really resolving the problem.

When it reconvened in December 1819, Congress had on its table a request for statehood from Maine. As a compromise, the Senate passed a bill allowing Maine to enter the Union as a free state, and Missouri to be admitted without restrictions on slavery. This was not the end of their problems, however.

When the Missouri constitutional convention empowered the state legislature to exclude free blacks, a new crisis was brought on. Enough northern Congressmen objected that the government called upon Mr. Henry Clay to draft the Second Missouri Compromise. On March 2, 1821, Congress stipulated that Missouri could not gain admission to the Union until it agreed that the exclusionary clause would never be interpreted in such a way as to abridge the privileges and immunities of U.S. citizens. Missouri forcefully agreed, and became the 24th state on Aug. 10, 1821; Maine had been admitted the previous March 15.

The compromise measures appeared to settle the slavery-extension issue, however, and the sectional conflict did not grow to the point of civil war until after the Missouri Compromise was repealed by the Kansas-Nebraska Act (1854) and was declared unconstitutional in the Dred Scott decision.