How were arguments over slavery dividing the nation?

How did settling the western territories cause further tension?

The North was afraid that the South would force its "peculiar institution" of slavery upon the entire Union. These fears were appreciated when the expansion of slavery into western territories entered Congressional debates. The federal government, hoping to prevent a civil war, temporarily resolved the issue with compromises. However, the compromises begun to be perceived as one sided resulting in increased sectional division between the North and South.