The EMP shutting down America thing is a disaster fantasy, disaster porn.
It is based on old technology.
A Carrington Event could take out a bigger chunk, but even then, not everything would go down.
Finally, to create an EMP someone would need to set off a large nuke above the Continental US. Consider, just for a second, what that would mean.
I know thinking about the US in a post apocalyptic wasteland will get the juices going on a Sunday morning. The thing is most fantasies are just make believe.
True. And it's pretty much a sure bet, the big question being when. Sometime in the next 100 years would be no surprise at all to those who follow what the Sun does, typically.
It would take more than one.