When Missouri requested admission to the Union as a slave state in 1819, this change represented a threat to the balance of power between slave and free states. The Missouri Compromise was then developed as an effort by Congress to defuse the conflict. This was a piece of legislation that allowed Missouri to join as a slave state with Maine admitted as a free state at the same time in order to maintain the balance in the Senate. Moreover, it prohibited slavery north of the 36°30′ parallel, excluding Missouri. After this compromise, political parties avoided the issue of slavery for years.
