a lot of the industrial base is in large cities, russia actually had a similar analog for this, after all they are very similar to america in terms of population distribution. the revolution began in the far spread out cities, mostly the big capitals like petrograd, moscow, and so on. cities like vladivostok even created revolutionary councils but the whites controlled the rural areas and quickly crushed them with american help due to how far away it was from the large metro areas in western russia. so if you live in say, the great plains and maybe the south, shit will probably not look so hot. but the pacific and east coasts would likely light up quickly and organize separately. the heartland would likely be the base of reactionary forces, especially the rocky mountains.

the soviets won the civil war by spreading their control outwards from the cities and into major, important rivers. the mississippi would be a big deal just like it was in the past civil war.

now, if its a simple coup that doesnt escalate into civil war, you can expect america to be very similar to latin american / western countries that had been couped, actually. coup followed up by massive civil action which either escalates into full blown fascism or a delayed ousting and leftists taking over.