I don't think any rational person disagrees that slavery was the key trigger to the secession or that a war was needed to end the practice. The south wanted to keep their slaves. Period. But you have to remember slavery is synonymous with the entire Southern economic system. Lincoln's win as an abolitionist just turned everything nuclear.
States Rights: It has been a LONG time since my college courses (1999?), but I do remember my professor talking repeatedly about the North hiring more immigrants/freed slaves and promising them land, then increasing tariffs on Southern goods to pay for this Westward expansion. The North was more industrialized with manufacturing and there were tariffs & taxes that were applied to the Southern import/exports that were not applied to the North because their products were so different. These manufacturers loved getting cheap cotton from Southern states and wanted to keep it that way. The Northern banks were charging higher interest payments to Southerners to cover losses some economic crash in the 1850s. There was also a tariff in the late 1850s that cranked up tariffs on Southern products +200%.
jk
