The Missouri Compromise involved a series of acts by the United States Congress in 1820-1821 to even out the number of free states and slave states in the Union. When Missouri petitioned for statehood in 1819, the number of free states and slaves were equal. A debated ensued whether Missouri should be admitted as a state that allowed slavery or as a state that prohibited slavery. Congress eventually reached a compromise, bringing in Maine as a free state and Missouri as a slave state, keeping the distribution even. The Missouri Compromise also defined how the slave versus free state debate would be handled in the future to avoid further debate.
Prior to Missouri seeking statehood, the 11 states did not allow slavery and 11 did. States with slavery were adamant about preserving their way of life, while abolitionists in Northern states were equally passionate about wanting slaves to be freed. Both free and slave states had equal representation in the Senate. However, the population in the free states was larger, giving the group a larger representation in the House of Representatives.
As Missouri was settled by Southerners, it was anticipated that the state would want to allow slavery. In 1819, James Tallmadge, a member of the House of Representatives from New York, offered an amendment seeking to prevent the further introduction of slaves in the Missouri territory and for slaves in the area to be freed. The measure passed the House but not the Senate.
The Missouri Compromise allowed both sides of the slavery issue to get something they wanted. In 1820 the Northern State of Maine was admitted to the Union as a free state. In turn, Missouri was allowed in as a state that allowed slavery. allowed the number of slave and free states to once again have the same amount of representation in Congress.
Besides bringing in one slave state and one free state to the Union, the Missouri Compromise also addressed how state slavery issues should be handled in the future. According to the compromise, the remainder of the Louisiana Purchase territory north of the southern boundary of Missouri would be slave free. The measure also asked for people in free states to return fugitive slaves to their owners.
Henry Clay, who served as Speaker of the House at the time, is credited with helping to spearhead the Missouri Compromise. The act was eventually signed by President James Monroe. The legislation did not permanently put an end to the slavery debate, and the Missouri Compromise was eventually revoked by the Kansas-Nebraska Act in 1854, which allowed the new settlements of Kansas and Nebraska to decide independently whether or not to allow slavery inside their boundaries.