In the south, slaves worked on plantations for all of their lives. They spent most hours of the day working, and if they were slacking, their masters would whip and/or punish them.
In the north, people were mostly unaware of the poor treatment of slaves in the south. In the north, people worked in factories, using the cotton from the south to produce clothes and other goods.
Slaves began to escape north, and this raised awareness to northerners who were finally getting a glimpse of what slavery was really like.
This led to the start of the American Colonization Society, which took slaves out of the south, and brought them to Africa. However, at this point, slaves were so Americanized that going back to Africa would not help them.
The second great awakening also sparked the question of slavery and the start of abolitionism when new beliefs and societies were formed.
The American Antislavery Society, formed by William Lloyd Garrison, a radical abolitionist, and Frederick Douglass, an escaped slave, fought for immediate emancipation.