The dividing line will be the entire states. In the densely populated Northern liberal states they will go along with the Federales. So yes, it will be state by state. The major cities in the South and mid west might have pockets of discontent but what are they going to do? Nothing. The jig will be up. They will be drafted and have to do their duty. The Welfare state will end. Or they can vote with their feet. The State is the next logical demarcation whether you think so or not.
I refer your fantasy to the answer I gave some moments ago.