What every General or Admiral will, and has stated concerning an EMP attack, it's not a question of "if", but of "when".

An enemy has 1 nuke, is it going to get the "biggest bang for the buck" by being used against a large city (a few million dead) or in an EMP tactic to maximize the effectiveness such as making the nudet approximately 300 miles above Kansas.

That would creat an EMP wave that would cover the entire USofA, Southern Canada, and northern Mexico. We will have been pushed back to the early to mid 1800's. All computers and electrical generators will be fried.

It is still being debated whether automobiles built after 1971 (1972 to the present) will still work or not.