Answer:
After this stalemate, Missouri renewed its application for statehood in late 1819. This time, Speaker of the House Henry Clay proposed that Congress admit Missouri to the Union as a slave state, but at the same time admit Maine (which at the time was part of Massachusetts) as a free state. In February 1820, the Senate added a second part to the joint statehood bill: With the exception of Missouri, slavery would be banned in all of the former Louisiana Purchase lands north of an imaginary line drawn at 36º 30’ latitude, which ran along Missouri’s southern border.
On March 3, 1820, the House passed the Senate version of the bill, and President James Monroe signed it into law four days later. The following month, the former President Thomas Jefferson wrote to a friend that the “Missouri question...like a fire bell in the night, awakened and filled me with terror. I considered it at once as the knell of the Union. It is hushed indeed for the moment. But this is a reprieve only, not a final sentence.”
Repeal of the Missouri Compromise
Though the Missouri Compromise managed to keep the peace—for the moment—it failed to resolve the pressing question of slavery and its place in the nation’s future. Southerners who opposed the Missouri Compromise did so because it set a precedent for Congress to make laws concerning slavery, while Northerners disliked the law because it meant slavery was expanded into new territory.
In the decades after 1820, as westward expansion continued, and more of the Louisiana Purchase lands were organized as territories, the question of slavery’s extension continued to divide the nation. The Compromise of 1850, which admitted California to the Union as a free state, required California to send one pro-slavery senator to maintain the balance of power in the Senate.
In 1854, during the organization of Kansas and Nebraska Territories, Senator Stephen Douglas of Illinois spearheaded the Kansas-Nebraska Act, which mandated that the settlers of each territory should decide the issue of slavery for themselves, a principle known as popular sovereignty. The controversial law effectively repealed the Missouri Compromise by allowing slavery in the region north of the 36º 30’ parallel. Passage of the Kansas-Nebraska Act sparked violence between pro- and anti-slavery settlers in “Bleeding Kansas,” delaying Kansas’ admission to the Union. Opposition to the act led to the formation of the Republican Party, and the emergence to national prominence of Douglas’s Illinois rival, a formerly obscure lawyer named Abraham Lincoln.
