How did the Missouri Compromise of 1820 effect relations between slave and free states?

 Congress passed a law that admitted Missouri to the Union as a slave state and Maine as a free state, while banning slavery from the remaining Louisiana Purchase lands located north of the 36º 30' parallel.

Explanation:

becasue in the south they disallowed slavery but in the north slavery was illegial this boilled into because mexico wanted slavery

a countries leader should be motivated by the common good of the country.