Missouri Compromise of (1820)

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 three-vote margin. Missouri and Maine were to be admitted to the Union simultaneously to preserve the sectional equality in the Senate.

Missouri Compromise (map showing boundaries of free and slave states).
ILLUSTRATION BY ERIC WISNIEWSKI. GALE GROUP

In 1821 Missouri complicated matters, however, by inserting a provision into its state constitution that forbade any free blacks or mulattoes (people of mixed Caucasian and African-American heritage) to enter the state. Northern congressmen objected to this language and refused to give final approval for statehood until it was removed. Clay then negotiated a second compromise, removing the contested language and substituting a provision that prohibited Missouri from discriminating against citizens from other states. It left unsettled the question of who was a citizen. With this change Missouri and Maine were admitted to the Union. The Missouri Compromise of 1820 merely postponed the conflict over slavery. As new territories were annexed to the Union, new compromises with slavery became necessary. The COMPROMISE OF 1850 redrew the territorial map of slavery and altered the 36° 30′ north latitude prescription of the Missouri Compromise. California was admitted as a free state, and the Utah and New Mexico territories were open to slavery. The KANSAS-NEBRASKA ACT of 1854 repealed the Missouri Compromise. This new law provided for the organization of two new territories that allowed slavery, Kansas and Nebraska, both north of the 1820 Missouri Compromise line of 36° 30′ north latitude. The land open to slavery drove deep into the north and west.

The constitutionality of the Missouri Compromise itself was challenged in the landmark U.S. Supreme Court case of DRED SCOTT V. SANDFORD, 60 U.S. (19 How.) 393, 15 L. Ed. 69 (1857). Scott, a slave, had lived with his master in the free state of Illinois and also in part of the Wisconsin territory, where slavery had been federally prohibited under the Missouri Compromise. After his master died, Scott sued in the Missouri courts for his freedom, on the grounds that he had lived in a free territory. The Supreme Court ruled against Scott, with Chief Justice ROGER B. TANEY holding that the FIFTH AMENDMENT denies Congress the right to deprive persons of their property without DUE PROCESS OF LAW. Therefore, the Missouri Compromise prohibiting slavery north of 36° 30′ was unconstitutional. The decision wiped away the Missouri Compromise but also raised the issue of whether slavery could be regulated by any government anywhere in the Union.