Where did the interests of the free and slave states diverge? What contradiction between

Where did the interests of the free and slave states diverge? What contradiction between them was the main reason for the Civil War?

The backbone of the production of the slave-owning southern states was export-oriented agricultural products. The main buyers were European states, England, France and others. In return, industrial goods were supplied from Europe. Industry developed in the Northern States, and European goods created competition for it. To protect its industries, the government imposes import duties on goods from Europe, which leads to higher prices and discontent in the southern states. In addition, the government is distributing new land in the west of the country to free farmers who create competition for the slave production of the southern states. All this led to a conflict between the Slave South and the industrial North, several Southern states declare themselves independent and create a confederation. The North imposes a naval blockade on the coast of the Southern States and a civil war begins.