New York and San Francisco were thrown into chaos after tens of thousands of homes and businesses lost electricity on Friday.
More than 90,000 homes in California were plunged into darkness and businesses were paralysed when the blackout started there just after 9am local time (4pm GMT).
The cut came just days after a former CIA director warned North Korean leader Kim Jong-un could knock out America’s national grid – killing nine in 10 Yanks.
San Francisco’s famous cable cars and traffic lights across the city stopped – causing mayhem.
Workers were stranded as the busy hub remained without power.
“Has to be either North Korea or Russia”
The “brownout” came shortly after another mysterious cut in New York – and conspiracy theorists have joined the two.
Matt Stock wrote on Twitter: “Power outage is spreading rapidly and still no news outlets reporting on it.
“Has to be either North Korea or Russia not a normal outage.”