After months of bitter debate, Congress passes the Missouri Compromise, a bill that temporarily resolves the first serious political clash between slavery and antislavery interests in U.S. history.
In February 1819, Representative James Tallmadge of New York introduced a bill that would admit Missouri into the Union as a state where slavery was prohibited. At the time, there were 11 free states and 10 slave states. Southern congressmen feared that the entrance of Missouri as a free state would upset the balance of power between North and South, as the North far outdistanced the South in population, and thus, U.S. representatives. Opponents to the bill also questioned the congressional precedent of prohibiting the expansion of slavery into a territory where slave status was favored.
Even after Alabama was granted statehood in December 1819 with no prohibition on its practice of slavery, Congress remained deadlocked on the issue of Missouri. Finally, a compromise was reached. On March 3, 1820, Congress passed a bill granting Missouri statehood as a slave state under the condition that slavery was to be forever prohibited in the rest of the Louisiana Purchase north of the 36th parallel, which runs approximately along the southern border of Missouri. In addition, Maine, formerly part of Massachusetts, was admitted as a free state, thus preserving the balance between Northern and Southern senators.
The Missouri Compromise, although criticized by many on both sides of the slavery debate, succeeded in keeping the Union together for more than 30 years. In 1854, it was repealed by the Kansas-Nebraska Act, which dictated that slave or free status was to be decided by popular vote in the territories of Kansas and Nebraska; though both were north of the 36th parallel.