Due to the growing conflict between slave states and free states in the early nineteenth century, the Missouri Compromise was drafted as a way to create agreement between the two sides prohibiting slavery in new territories in the former Louisiana territory except for the newly formed state of Missouri which would be a slave territory. Any area above the parallel of 36 30 north would be designated as free territory.
During its passage through congress the measure also acquired the admittance of Maine and Alabama as free and slave states respectively, thus equaling the number of slave and free states in the Union.
Jefferson, among others, felt that this division would eventually lead to a divided nation and the act was eventually repealed by the Kansas-Nebraska Act in 1854.
The Missouri Compromise included that Maine would enter the Union as a free state. Missouri would enter the Union as a free state. The remaining territory of the Louisiana Purchase would be closed to slavery.