The civil War was not about slavery. The south seceded when it realized that it would a permanent political minority.
This ignores the fact that the source of *MONEY* which was paying for the government came 73-85% from Southern produced exports. (For which imports were payment.)
I have come to believe that the slavery issue was just a means of keeping the South in a position so that it could not change a system that was causing a large amount of money to flow into New York and Washington DC.
Liberals today try to use wedge issues like "Abortion", "Racism", "LGBT", and "Healthcare", to convince voters to keep them in power. In the 1850s, they used the Slavery issue to do it, yet when it came to the South leaving, they voted to pass the Corwin amendment, because they wanted to keep that money flowing.
I now think much of the public speaking on the issue of Slavery was Kabuki Theater to secure political power, and the concern over the "expansion of slavery" was just astroturf and interest groups.