William Graham, a top scientist who once served as a national science advisor to President Reagan, reported to Congress, warning of the risk of EMP weapons to the U.S., if measures weren't taken to secure our infrastructure from such an attack.
"Theoretically, an EMP attack is devastating because of the unprecedented cascading failures of major infrastructures that could result. Because of America's heavy reliance on electricity and electronics, the impact would be far worse than on a country less advanced technologically."
This document is of the 2008 report and includes some quotes from experts who testified on the consequences of EMP weapons being used against the U.S., as well as some concerning facts on how quickly we could expect to recover. Also covered is what America is looking at in regards to preparing for this type of event.
As is always being said, it's best to be in the know on important matters and be prepared, than to lack the necessary skills to survive an emergency situation.