The Missouri Compromise of 1820 was a congressional agreement that regulated the extension of SLAVERY in the United States for the next 30 years. Under the agreement the territory of Missouri was admitted as a slave state, the territory of Maine was admitted as a free state, and the boundaries of slavery were limited to the same latitude as the southern boundary of Missouri: 36° 30? north latitude.
The issue of slavery had been troublesome since the drafting of the Constitution. Slave-holding states, concerned that they would be outvoted in Congress because their white population was much smaller than that of the free states, extracted concessions. Under the Constitution, representation of the U.S. House of Representatives was based on the total white population and three-fifths of the black population. The Constitution apportioned two senators for each state.
By 1820, however, the rapid growth in population in the North left Southern states, for the first time, with less than 45 percent of the seats in the House. The Senate was evenly balanced between eleven slave and eleven free states. Therefore, Missouri's 1818 application for state-hood, if approved, would give slave-holding seats a majority in the Senate and reduce the Northern majority in the House.
After a bill was introduced in the House in 1818 to approve Missouri's application for state-hood, Representative James Tallmadge of New York introduced an amendment that prohibited the further introduction of slavery in Missouri and required that any slave born there be emancipated at age 25. The bill passed the House but was defeated in the Senate, where Southern strength was greater.
In 1819 the free territory of Maine applied for statehood. Speaker of the House HENRY CLAY of Kentucky saw this event as an opportunity to maintain the balance of free and slave states. He made it clear to Northern congressmen that Maine would not be admitted without an agreement to admit Missouri. Clay was successful, getting the Northern congressmen to drop their amendment restricting slavery while winning Southern congressmen over to the idea of limiting slavery to the 36° 30? north latitude. This provision, in effect, left unsettled portions of the LOUISIANA PURCHASE north and west of Missouri free from slavery. The only area remaining for further expansion of slavery was the future territory of Arkansas and Oklahoma. Clay managed to pass the compromise in the House by a...