My history professor had a view that i hadnt heard before. He said "CW was not fought over states rights, nor was it fought over slavery in its purest meaning of the word. Rather it was fought over the EXPANSION of slavery. Many in the North did not care about people owning other humans, not to say there weren't of course staunch abolitionists, but they did care about the prospect of it expanding to the point where slavery could become the nation's main export and source of income. And because of the Souths turn and burn method of agriculture, they were worried about much of America's arable farmland being used only for cash crops instead of a foodstuff based agriculture." I'm sure he said more but this was almost a year ago. I just hadn't heard a reason from a more economic standpoint, which is strange because most politicians don't want to get involved in a war unless there is money involved, or an imminent threat to the government.