THE MISSOURI COMPROMISE
As a result of (the growth of the cotton industry), slavery took on a new vitality in the South...the attitude toward it was transformed. At the time of the American Revolution the institution was deemed by most southern leaders an unmitigated curse. By 1820 it was apologized for as an evil to be alleviated by spreading it out thin over the West (Henry Clay's position). By 1837 Calhoun and other southern writers were defending slavery as a positive good. By the 1850's southern clergymen were eulogizing slavery as a divine institution , sanctioned by the Bible and approved by God. The prospect of dislodging it by gradual emancipation vanished.
The first serious sectional clash over slavery occurred in 1819, when Missouri applied to Congress for admission to the Union as a state. Slavery was then still common in the North. Admission of Missouri to the Union as a slave state would upset a balance in the Senate. To prevent this, Tallmadge of New York proposed restrictions on Missouri's admittance. A crisis ensued because the policy would admit Missouri to the Union as a "less than equal" state with the other ones. The Missouri Compromise resulted and sought to alleviate states-rights concerns.
Missouri was admitted to the Union without restrictions, Maine was added as a free state, and the remainder of the Louisiana Purchase north of the line of 36° 30' was closed forever to slavery. An issue was later raised over whether Congress could impose such restrictions on a territory, but at least the dangerous crisis over Missouri had been resolved.
Information from History of the Western Movement , by Frederick Merk
