The correct answer to this open question is the following.
Abolitionism and the prospect of the emancipation of enslaved people lead to conflict between Northern and Southern states because these ideas confronted citizens of the United States that were against slavery and were called abolitionists, with the people from the southern states that supported slavery.
Landlords in the southern states owned big portions of land. They needed extra hands to work on the farm fields in order to produce the number of crops needed to trade and export to Europe. That is why they had slaves that worked for long hours in the fields. Indeed, the southern states based their economy on slaves.
On the other hand, people from the North supported the emancipation of slaves and demanded the abolition of slavery in the south. Of course, the polarization of these ideas caused many conflicts and ended up being one of the main causes of the American Civil War.