Also Z, If (and only if) the ENTIRE continental US was EMP'd, I would argue that it would take us back further than the 1950s. Probably closer to the 1930s in some regards, and back into the 1800s in others. The whole power grid, distribution of food, fuel and other resources, as well as nearly all communication would be down for months, if not a year or more. All of our manufacturing uses technology that would go "POOF!" in an EMP. We would be starting a lot of things from scratch.

If it was just one part of the continental US, then we would be mostly back up and running withing a few months, but things would be awfully ugly in the meantime.