Missouri Compromise

In 1818, the population living in the Missouri Territory was large enough to qualify it to become a state.   But would it enter as a slave or a free state ?

Congress was bitterly divided on the matter until a Compromise was passed in 1820 that permitted Missouri to enter as a slave state, while Maine (previously the northern part of Massachusetts ) entered as a free state .  Therefore, the balance between slave and free states remained at 12-12. 

The Compromise drew a line at 36 degrees, 30 minutes north latitude across the territory of the Louisiana Purchase .  Any states created north of that line would be free; south of that line slavery would be permitted.  The Compromise also included a fugitive slave provision, requiring runaway slaves who succeeded in reaching free territory to be captured and returned to their masters. 

The Missouri Compromise was ruled unconstitutional by the Supreme Court in the 1857 Dred Scott decision.  The court said that Congress did not have the power to block slavery from any territory in the country.