Why was slave labor not as important to the north as it was to the south?

The entire economy of the South depended on slavery. There were many compromises initiated to determine whether new territories came in as slave states or free states. The question of whether states had more rights than the federal government lasted for 40 years before the Civil War. The question existed whether states could secede from the Union if they so desired. There was a large group of abolitionists who wanted to end slavery, which would have destroyed the economic, social, and political structure of the South.

The theory is land mass basically what they said.