Stores emptied out, and Broadway shows did not go on: Most theaters canceled their performances. In restaurants and bars, people drank by the glow of their smartphones.
But the lights began to return about 10 p.m. Power was fully restored by midnight, with cheers ringing out on the streets in response.
Con Edison said that the power failed at 6:47 p.m. and that 73,000 customers were in the dark for at least three hours.
The utility said the failure apparently stemmed from a problem at a substation. John McAvoy, Con Edison’s chairman and chief executive, suggested it was a mechanical failure but emphasized that the utility would not know the cause until an investigation was completed.
The blackout happened on the same date that a large power failure in 1977 plunged the city into darkness.
At intersections, police officers and civilians worked to direct traffic while firetrucks and ambulances screamed down side streets. Two young women posed for a selfie in the middle of one street before an officer rushed over and chastised them, saying, “Ladies, this is not the time.”
The Metropolitan Transportation Authority, which runs the subway, said the blackout affected the entire system, with limited service for a time on several lines.
Most Broadway shows — including “Moulin Rouge! The Musical,” “Hadestown,” “Harry Potter and the Cursed Child” and “Aladdin” — canceled their performances. On the sidewalks outside, the casts staged impromptu shows.
Carnegie Hall canceled all performances. At Lincoln Center, a performance from the Mark Morris Dance Group was canceled, but outside, the Midsummer Night Swing band kept going.
At the Jennifer Lopez birthday-themed extravaganza at Madison Square Garden, the power failure happened during the fourth song. Suddenly, the lights went dark, and the speakers fell silent. The only sound was a live drum set, still playing as dancers continued their routine.
After a while, a backup generator kicked in, and the lights came on. Minutes after that, a high-pitched chime sounded, and the audience was told to leave.