How did the Missouri Compromise split the western territories in two?

It split the western territories into two because most of the state's in the north did not have slaves but in the south they did. Not only that but also because when the south made the cotton for the clothes they would make in the north and when they would sale it to the south they would have it cost a lot like 2times it was worth so the south had gotten angry over that and the north was annoyed then came the civil war. basically they hated each other then