So, I've kind of wondered about this from across the pond. It's not so much a question of the country being divided, it's a question of how the divide seems to prevent the government from actually governing, and where everything is a partisan competition. Heck, Republicans might even welcome it, if we factor in demographic change being unfavourable to them.
On the other hand, I'd like to point out that:
-That map is crazy as hell. The red states are at least all connected bar Alaska, but the blue states are fragmented.
-This isn't my conclusion, but I remember reading somewhere about how independence movements in recent history have rarely worked out. Eretria separated from Ethiopia, and that led to the former falling to dictatorship, and the latter losing access to the sea. South Sudan became independent from (north) Sudan, and fell into civil war. Independence and self-determination sounds good, but it can lead to a lot of problems.
-Saw another suggestion that the US should be more like the EU. As in, in this case, every state should be fully sovereign, but be part of a greater trading bloc. I could see this helping states like California and Texas at least, which I understand are economic powerhouses, and both have toyed with secession regardless of the blue/red divide.
-Balkanization is a thing, and it ain't pretty. On the other hand, the British Empire and Soviet Union disbanded fairly peacefully, and the former led to the Commonwealth, so maybe there's a template. Or maybe it'll lead to war, and red and blue soldiers will be sent to box canyons asking why they're there.
I mean if such extreme measures are to be taken, we may as well just give all Mexican land back to México since we stole it from them...
Shhhh, don't tell them.
Didn't Mexico technically steal it from Amerindians?
The whole "stolen land" argument has never worked for me, because apart from a handful of places on the planet, every piece of real estate is stolen. We're actually in an atypical point in human history where the amount of land grabs (as in, states invading other states) is at an all-time low.