The EMP wouldn't kill Americans. Americans would kill Americans, for food, clothing, shelter, decades and centuries of perceived slights, and just because they can. Water pumps wouldn't work to pump water, gas pumps wouldn't work for food transport, agricultural equipment would work to make food. All the preppers would be forced to kill anyone within a half mile of their homestead, or get what the stored taken. People wholly dependent on the government for their day to ay existence would die, anyone who requires medicine or medical equipment would die. Anyone who couldn't hunt scrounge and defend what they had would die. While 90% of America would die, 100% of North Korea or any country that intitiates a EMP attack would die.