What could possibly cause a second American Civil War?
I think ACW2 (kind of an awkward acronym) would most likely be caused the US national debt. The national debt would start to push inflation rates higher and higher until dollars are virtually worthless. Texas would move onto either a gold backed currency or a virtual currency and secede from the United States, followed by all the angry Southern states that never got over ACW1. If Obama was still president, he would just let them go. If we had anyone else as president they would fight to retain the union.