From Daily Mail (tabloid):
The United States is at risk of a nationwide blackout that could last 18 months, according to the former chairman of the Federal Energy Regulatory Commission.
Jon Wellinghoff became aware of the alleged vulnerability after a shooting at a Pacific Gas and Electric Company’s San Jose substation, according to the The New York Times Magazine. He conducted a power flow analysis that modeled the large-scale effects of knocking out the most critical substation in each of America’s three power grids: the Western, Eastern and Texas interconnections. He said this led him to discover just how easy it would be to cripple America’s power supply.