Answer:
The tension regarding slavery was one of the main factors that triggered the secession of the southern states and the subsequent Civil War in 1861.
Historically, the north of the country had been a more progressive society with liberal tendencies, which supported the abolition of slavery. It was also an economically advanced society, thanks to industrialization and the large ports of its cities. Instead, to the south of the country was a more traditionalist and conservative society, which protected its economic progress in slave labor that exploited agricultural and livestock production, and therefore supported slavery and its legality.
Over the years, various social and political conflicts between abolitionists and slavers emerged, with different results such as the Missouri Compromise, the 1850 Compromise or Bleeding Kansas. But finally, when in 1860 Republican Abraham Lincoln, who was accused of being abolitionist by the southern Democrats, won the presidential elections, the southern states decided that, faced with the hypothetical danger of the abolition of slavery, it would be better to separate from the rest of the country and found a nation based on slavery, the Confederate States of America.