The Missouri Compromise (also known as the Compromise of 1820) was federal legislation of the United States that balanced the desires of northern states to prevent the expansion of slavery in the country with those of southern states to expand it. It admitted Missouri as a slave state and Maine as a free state and declared a policy of prohibiting slavery in the remaining Louisiana Purchase lands north of the 36°30′ parallel. The 16th United States Congress passed the legislation on March 3, 1820, and President James Monroe signed it on March 6, 1820.
Earlier, in February 1819, Representative James Tallmadge Jr., a Democratic-Republican from New York, had submitted two amendments to Missouri's request for statehood that included restrictions on slavery. While the slave states earlier claimed federal protection for slavery, they now objected to any bill that imposed federal restrictions on slavery and claimed that it was a state issue, as settled by the Constitution. However, with the Senate evenly split at the opening of the debates, both sections possessing 11 states, the admission of Missouri as a slave state would give the South an advantage. Northern critics including Federalists and Democratic-Republicans objected to the expansion of slavery into the Louisiana Purchase territory on the Constitutional inequalities of the three-fifths rule, which conferred Southern representation in the federal government derived from a state's slave population.
Northern Democratic-Republicans ardently maintained that a strict interpretation of the Constitution required that Congress act to limit the spread of slavery on egalitarian grounds. "[Northern] Republicans rooted their antislavery arguments, not on expediency, but in egalitarian morality." "The Constitution [said northern Democratic-Republicans], strictly interpreted, gave the sons of the founding generation the legal tools to hasten [the] removal [of slavery], including the refusal to admit additional slave states."
When free-soil Maine offered its petition for statehood, the Senate quickly linked the Maine and Missouri bills, making Maine's admission a condition for Missouri entering the Union as a slave state. Senator Jesse B. Thomas of Illinois added a compromise provision that banned slavery from all remaining lands of the Louisiana Purchase north of the 36° 30' parallel. The combined measures passed the Senate, only to be voted down in the House by Northern representatives who held out for a free Missouri. Speaker of the House Henry Clay of Kentucky, in a desperate bid to break the deadlock, divided the Senate bills. Clay and his pro-compromise allies succeeded in pressuring half of the anti-restrictionist Southerners in the House to submit to the passage of the Thomas proviso and maneuvered a number of restrictionist northerners in the House to acquiesce in supporting Missouri as a slave state. While the Missouri question in the 15th Congress ended in stalemate on March 4, 1819, with the House sustaining its northern anti-slavery position and the Senate blocking a state that restricted slavery, it succeeded in the 16th Congress.
The Missouri Compromise was controversial. While it mollified most people at the time and settled the issue for more than 20 years, many worried that the country had become lawfully divided along regional and sectarian lines. Tensions resumed in the 1840s and the Compromise of 1850 only briefly defused the situation. The Kansas–Nebraska Act effectively repealed the bill in 1854, and the Supreme Court declared the Missouri Compromise unconstitutional in Dred Scott v. Sandford (1857), both of which increased tensions over slavery and contributed to the American Civil War. The compromise both delayed the Civil War and sowed its seeds; in April 1820, Thomas Jefferson predicted the line as drawn would someday tear the Union apart. Forty years later, the North and South would split closely along the 36°30′ parallel and launch the Civil War.
The Era of Good Feelings, closely associated with the administration of President James Monroe (1817–1825), was characterized by the dissolution of national political identities. With the Federalists discredited by the Hartford Convention against the War of 1812, they were in decline nationally, and the "amalgamated" or hybridized Democratic-Republicans adopted key Federalist economic programs and institutions, further erasing party identities and consolidating their victory.
The economic nationalism of the Era of Good Feelings authorized the Tariff of 1816 and incorporated the Second Bank of the United States, which portended an abandonment of the Jeffersonian political formula for strict construction of the Constitution, a limited central government, and commitments to the primacy of Southern agrarian interests. The end of opposition parties also meant the end of party discipline and the means to suppress internecine factional animosities. Rather than produce political harmony, as President James Monroe had hoped, amalgamation had led to intense rivalries among Democratic-Republicans.
It was amid that period's "good feelings" during which Democratic-Republican Party discipline was in abeyance that the Tallmadge Amendment surfaced.
Louisiana Purchase and Missouri Territory
The immense Louisiana Purchase territories had been acquired through federal executive action, followed by Democratic-Republican legislative authorization in 1803 under President Thomas Jefferson.
Prior to its purchase in 1803, the governments of Spain and France had already sanctioned and promoted slavery in the region. Enslaved African Americans accounted for twenty to thirty percent of the non-Native American population in and around the main settlements of St. Louis and Ste. Genevieve. In 1804, Congress limited the further introduction of enslaved men and women to those introduced by actual settlers.
In addition, in appointing the officials from the Indiana Territory to Upper Louisiana (as Missouri was known until 1812), Congress heightened concerns that it intended to extend some sort of prohibition on slavery's growth across the river. White Missourians objected to these restrictions, and in 1805, Congress withdrew them. The final version of the 1805 territorial ordinance omitted all references to slavery. Under the 1805 ordinance, slavery existed legally in Missouri (which included all of the Louisiana Purchase outside of Louisiana) by force of local law and territorial statute, rather than by territorial ordinance, as was the case in other territories where slavery was permitted.
It is unknown if Congress purposely omitted any reference to slavery or Article VI in the 1805 territorial ordinance. Nonetheless, over the next fifteen years, some restrictionists – including Amos Stoddard – claimed that this omission was deliberate, intended to allow the United States government to prohibit slavery in Missouri if circumstances proved more favorable in the future.
In 1812, Louisiana, a major cotton producer and the first to be carved from the Louisiana Purchase, had entered the Union as a slave state. Predictably, Missourians were adamant that slave labor should not be molested by the federal government. In the years after the War of 1812, the region, now known as Missouri Territory, experienced rapid settlement, led by slaveholding planters.
Agriculturally, the land in the lower reaches of the Missouri River, from which that new state would be formed, had no prospects as a major cotton producer. Suited for diversified farming, the only crop regarded as promising for slave labor was hemp culture. On that basis, southern planters immigrated with their chattel to Missouri, and the slave population rose from 3,101 in 1810 to 10,000 in 1820. Out of the total population of 67,000, slaves represented about 15%.
By 1819, the population of Missouri Territory was approaching the threshold that would qualify it for statehood. An enabling act was provided to Congress empowering territorial residents to select convention delegates and draft a state constitution. The admission of Missouri Territory as a slave state was expected to be more-or-less routine.