Besides the subway and the stock exchange, most major tunnels and bridges in New York were closed, as were schools, Broadway theaters and the metropolitan area's three main airports, LaGuardia, Kennedy and Newark.
"This will be one for the record books," said John Miksad, senior vice president for electric operations at Consolidated Edison, which had more than 670,000 customers without power in and around New York City.
The death toll climbed rapidly, and included 17 victims in New York State — 10 of them in New York City — along with four dead in Pennsylvania and three in New Jersey. Sandy also killed 69 people in the Caribbean before making its way up the Eastern Seaboard.
In New Jersey, a huge swell of water swept over the small town of Moonachie, near the Hackensack River, and authorities struggled to rescue about 800 people, some of them living in a trailer park.
And in neighboring Little Ferry, water suddenly started gushing out of storm drains overnight, submerging a road under 4 feet of water and swamping houses.
Police and fire officials used boats and trucks to reach the stranded.
"I looked out and the next thing you know, the water just came up through the grates. It came up so quickly you couldn't do anything about it. If you wanted to move your car to higher ground you didn't have enough time," said Little Ferry resident Leo Quigley, who with his wife was taken to higher ground by boat.
Jersey City was closed to cars because traffic lights were out, and Hoboken, just over the Hudson River from Manhattan, dealt with major flooding. In Atlantic City, most of the world-famous boardwalk was intact, but pieces washed away Monday night.
Remnants of the hurricane were forecast to head across Pennsylvania before taking another sharp turn into western New York by Wednesday morning. Although weakening as it goes, the storm will continue to bring heavy rain and flooding, said Daniel Brown of the National Hurricane Center in Miami.