Alternate Civil War

Just an idea I had going though my head. The POD is that Congress uses the Mason-Dixon line as the border between the slave states and free states. This results in 3 alternate states*, no Bleeding Kansas, and equal representation in both the House and Senate. This map shows the US prior to the 1860 election, whoever wins will grant Kansas and Nebraska statehood and keep slavery going for another four years if nothing goes wrong.

Now here comes your guy's part. You tell me what should happen and I'll put the ideas in the sequel.


*You guys can pick the names.