The blackout prompted traffic and pedestrian chaos
Shows on Broadway, New York, had to be cancelled following a series of power failures which hit the eastern side of the United States and Canada.
More than 25 popular productions such as The Lion King, The Producers, and 42nd Street all had to be cancelled, as well as 16 off-Broadway shows.
Ushers and box-office staff were sent home, along with actors as the lights and air-conditioning went off.
Fans filled the pavements outside the New Amsterdam Theater on 42nd street, where a sign on the door said The Lion King had been cancelled "due to circumstances beyond our control".
Diane Baskin, from Michigan, had come to New York with her 20-year-old daughter, Jill, to see Gypsy.
"We're just people-watching," said Jill. "You've got to make the most of it," added her mother.
Refunds or exchanges would be available from the place of purchase, said Jan Svendsen, a spokeswoman for the League of American Theatres and Producers.
"We only bought the tickets at three o'clock and the power went at four," said Ken Slater from Derry, New Hampshire, who paid $315 (£196) for three tickets.
The last time all of Broadway shut down was after 11 September, when the lights went dark the day of the bombing and the next.
A musicians' strike closed musicals, but not plays, for four days earlier this year.
Millions of people have been affected by a series of power failures that hit major cities in the eastern United States and Canada.
Blackouts spread from New York to Detroit, and Toronto to Ottawa, causing chaos as traffic lights failed, underground railways were evacuated and people were trapped in lifts in offices and apartments.
Canadian officials said a fire at a power plant near the upstate New York town of Niagara caused the outage - at about 1610 local time (2110 GMT) - which then cascaded across the country.
The US Department of Homeland Security said it was investigating the cause of the blackouts but US officials - who dispute the Niagara theory - have said there is no evidence terrorism is to blame.