For what it’s worth, I spent a lot of time studying the CW for the past few years as a hobby. The states rights thing came down to equal enforcement of federal policy.

Around 1830 prior, South Carolina was denied the ability to set its own port tariff when it tried to assert states rights. See Tariff of Abominations. When the fugitive slave act wasn’t enforced it was seen as northern legal bias. This was a big deal because it was already seen as big problem. Around the time of the war, 80% of the US federal tax revenue came from the south while most spending benefited the north.

The root cause of the war was absolutely slavery, but when people say there were a lot of contributing factors...they aren’t kidding. Including parts that nobody on either side wants to talk about.

The history is really interesting and studying it goes a long way toward helping to understand how we got to where we are as a country today. 150 years ago or not, we still feel the effects today.