The report of the commission to assess the threat to the United States from Electromagnetic Pulse Attack is too long for most mere mortals to read. But everyone should at least make an effort to read chapter one (skip the introduction and scroll down to page 17).
The commission details how the US electrical grid has become increasingly vulnerable to all forms of disruption, not just EMP Attacks. Like the various reports that detailed the problems with the levees that held back the water around New Orleans, this report is going to be ignored. It will only receive widespread press once the grid goes down.
And as the report makes clear, the electric grid is very vulnerable and becoming more vulnerable with every passing day. Vulnerability to EMP attacks is simply the tip of the iceberg. An increasing shortage of black start capability combined with a shortage of parts means that simply blowing up a few key transformers could cause major problems.