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 (Jeffersonian 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.
