I think a key problem you run into here is while the division is very clear, it's spread all over.

Even if you pick out a place that stands out as very conservative, let's say Arkansas--you've got fairly strong Democrat counties directly bordering strong Republican counties. Texas is even worse in this regard. Austin is not at all politically similar to pretty much anything outside of it's metro area.

So what do you do, split them up and force people to migrate?