One side would devolve into an unlivable hellscape. The other side would devolve into the 1890s-1910s or so, without access to modern imported goods.
Nobody would "win". It's obviously a horrible scenario. But one side would definitely lose.
> It can't happen without something freakish happening
Nations collapse from political schism all the time. We just have short memories.
I do not believe the people yelling "secession!" are prepared to revert to a pre-WWI world.
And if your supply requirements decrease by 150MM people, that makes the job substantially easier to manage.
> I do not believe the people yelling "secession!" are prepared to revert to a pre-WWI world.
Ah, but they think they are. Which is really the only thing that matters, since beyond a certain point, it's too late.
Subsistence farming is great for feeding an army so you can rebel against your government
This is why I said all the current informal federal-based stuff would come back through treaty. I think most people on both "sides" are reasonable, so the split would never actually happen. And if it did, people would quickly miss all the stuff from the other side of it.
It's on a level with considering what happens if the sun disappears. It can't happen without something freakish happening, and none of us really knows how it would go.