The buildup to the war was about slavery. The aftermath of the war was about what we replaced slavery with... and it’s not pretty.
Here’s an article with a few book recommendations to get you started. https://www.bostonglobe.com/arts/2015/04/25/seven-books-reco...
I personally recommend “Reconstruction, America’s Unfinished Revolution” by Eric Foner. It’s a solid read but well worth it in my opinion.
If you're looking for an analogy to American politics as "second civil war", it won't help. But if you're looking for how two sides are willing to destroy themselves trying to destroy each other, it's amazing.
/r/AskHistorians' Book List might be cover pretty much anything else:
But from the civil war to Julius Caesar was only 30 years...