@epictittus @YourAverageNewfag @Shadowman311 @TrevorGoodchild Depends also on how much power retains the central government before going to shit, and what it wants to do.
Enough to defend? can still project power? armed forces as well, if they draft people en masse won't take much long before it goes from bad to worse.

> small size of the region

Yes, absolutely, but still, when it started it was almost everywhere, no escaping it, even if you were considerably behind the lines dangers were all over.
In America this won't be as likely, specifically for the size of the scenario, some areas won't be touched if not marginally , others will be overrun by the consequences, the coasts and metro areas I see them performing poorly, very poorly, both in terms of casualties and in terms of degradation, infrastructures, quality of life etc, everything will be affected.
NY / LA are very likely to collapse as soon as the roads won't bring the goods in, looting will peak and bands will be formed, these will be then become more or less popular based on how they act as long as there is wealth to distribute, once that ends they will have to venture off, to evolve into something else, niggers will probably loot everything to the ground and move to the next target until they stumble on a wall and starve.
This is why I expect to turn on ethnic bases very quick.
And then, among these, there may be room for a political or religious or anything else to form a subsection.

> in a way that nothing ever has in human history

Agreed, again.
It may last a decade or more, is very likely to spill over to both CAN and MEX and possibly CENAM too, expecially if large groups of spics will try to move back to their country of origin.
No huge coalitions because the land is fractioned , small convenience alliances here and there among similar groups would be a possibility, for example, perhaps Texas holding its own , banding together with other states in similar positions and bulking around it?

Spanish civil war had a massive influx of foreigners from the beginning, they considerably tilted (the pro-Nationalist were good and disciplined fighters, the red ones awful shit stirrers) the outcome, but mostly prolonged the war.
Don't doubt away teams may want to play the game in the american league, but oceans will still play a factor and won't be as relevant, at least at the beginning.