I want you to look at that again, and look at how many ports blues control, vs reds.
The interior blue areas might have issues, but the coasts can just go to foreign suppliers for many things.
A lot of things can be imported, but
food is the biggest problem. The USA is the largest exporter of food in the world; if there's a civil war and coastal cities are trying to source food from elsewhere,
who are they going to import it from? They'll be able to bring in
some, but they have to make up not just for what they aren't getting from the interior anymore, but they're also suddenly competing to buy in a market that has had its' biggest provider dry up.
It also means they will likely control most of the Navy, and can interdict the few red ports rather easily. The blues also control most of the Southern border, so good luck getting supplies via Mexico, and I doubt Canada will help.
If an actual hot civil war breaks out, the 'red states' and red areas aren't going to have the same kind of
need for imports. Food is an urgent and immediate need, one which can make you lose the conflict in days and weeks. The only other things that can make you lose so quickly if you run out are water, ammunition, and fuel.
Of these, rural areas already use their own wells and pumps, and most people who own firearms stockpile hundreds to thousands of rounds of ammunition. Fuel is a genuine concern, but oil industry tends to be centered in conservative-dominant areas as well, so it's not an immediately resolved issue one way or the other.
Also, how do the reds plan to deal with the blues orbital assets, which can give them massive advantages? I doubt the reds would have access to anything close to much in terms of AA or air power, never mind ASAT, weaponry.
Anyone who thinks the reds have anything approaching good odds is a fool that is ignoring the geographic, technical, and international realities such a conflict would take place in.
What would happen to the military is
way too much of a toss-up to definitively call either way. Even with how much the left has been trying to ram their agenda into the military lately, it has a strong preponderance towards conservatism,
especially the combat arms. Acting like the left would have it as a foregone conclusion is silliness.
The reason that people keep bringing up the food issue, is because unlike war in the 1860's, where we were still a primarily agrarian nation and most people either fed themselves, or lived within walking distance of the people that produced the food they purchased, most people in the modern day have
no clue how to go from 'raw materials' to 'food I can eat.'
People generally only keep enough food in their house to last a few days to a week before they're eating plain canned beans, if they have that. Grocery stores with supply shipments cut off will be out of 'preferred' stock in a day or two, and completely stripped bare within a week, if people
don't go raiding to stockpile food.
Practically speaking, two weeks is the amount of time it would take where food goes from 'this is a problem we need solved in the near future' to 'there are food riots in the street.'
Two weeks isn't long enough to whip a competent militia into shape, that could go out and try to seize crops or live-stock. If you have people who are capable of recognizing a problem, formulating a solution, and acting quickly and decisively, you could have a loosely-controlled armed mob going out to try to do the same by then, but...
The modern left isn't exactly known for their institutional competence or ability to act quickly and decisively, is it?
In the end, there are too many factors in play to know how a civil war in the USA would go. It's been 160 years since we last had one, and the automobile didn't exist back then, much less the airplane, the automatic rifle, the radio, the internet, etc. There's too many factors in play, that have
never been tested in a civil war type of conflict, to say anything with any
real certainty.
There's a certain
weight though, to 'these people know how to produce their own food and use it, and these other people do not.' If any conflict lasts long enough, that'll be pretty damned decisive in its own right.
If.
Honestly, I'm starting to think regional control of the electrical grid will probably be more decisive. If someone decides to start shutting off power to other areas, there's not a lot of incentive for the people in that area not to then blow up major transmission hubs or power plants. If that happens, pretty much everyone in the region is screwed.