Which issues played the greatest role in dividing the north and south in the years leading up to the civi war

While Northern states wanted to abolish slavery, Southern states defended slavery. This difference was the biggest reason that led to the Civil War.

Northern States focused their economy on industries, they were an urban society were slavery had practically disappeared and most people worked on factories.

Southern states focused their economy on agriculture, they relied on slaves to work on their plantation crops of cotton, rice and tobacco.

Southern states felt threatened with the election of Abraham Lincoln in 1860, fearing that their way of life would end because he wanted to abolish slavery, this caused the Southern secession that led to the Civil War.