In the 1800s, the United States new western territory became a battleground over slavery. Abolitionists in the north wanted slavery outlawed in all new states. Slaveholders in the south wanted slavery to be allowed. People in the south thought that new states should have the same freedom of choice that the original 13 states had. Slaveholders also worried that they could not stop anti-slavery legislation in Congress if more of the new states were admitted as a free states.
In 1819, leaders in the Missouri Territory asked to make Missouri a slave state. Abolitionists opposed the request. In 1820, they reached what was called the Missouri Compromise, also known as the "Compromise of 1820."
Details of the Missouri Compromise:
Missouri would be admitted as a slave state.
Maine would be admitted as a free state.
Congress drew a boundary across the west, determining the free areas to the north and slave regions to the south of the line.
The Missouri Compromise worked for nearly 30 years. The policy allowed for the expansion of the country. There were an equal number of free states and slave states, so neither side gained political control. Each time a slave state was admitted, a free state was also admitted. However, the Missouri Compromise further divided the country between North and South.