Purple America. There's a thin strip of hardcore blue from Seattle to southern Texas hugging the border and the east coast Blue U, known as the Sprawl. There's also the Red Crescent of the Mid West into the upper Rockies. Aside from that, it's all purple. If the US cracks, the odds of a peaceful stereotyped Coastals vs Middle America is a pleasant but unrealistic fantasy. Think urban and suburban warfare that'd make Iraq look like a Sunday picnic.
The only stereotypical aspects would be a lot of landlocked red country and a lot of easily seiged blue cities. Neither side holds a strategic advantage.
Hehe. Much of the core infrastructure- railway depots, harbors, power generation, refineries, heavy industry, and warehousing is
deep in the blue areas- places that would require something of a military presence to keep operational if things did fall apart.
A balkanized America would be a race to the bottom, not a competition to see who comes out on top.