The full extent of the damage in New Jersey, where the storm roared ashore Monday night with hurricane-force winds of 80 mph, was unclear. Police and fire officials, some with their own departments flooded, fanned out to rescue hundreds.
More than 8.2 million people across the East were without power. Airlines canceled more than 15,000 flights around the world, and it could be days before the mess is untangled and passengers can get where they're going.
The storm also disrupted the presidential campaign with just a week to go before Election Day.
President Barack Obama canceled a third straight day of campaigning, scratching events scheduled for Wednesday in swing state Ohio, which got clobbered by Sandy's winds as the storm pushed west. Republican Mitt Romney resumed his campaign, but with plans to turn a political rally in Ohio into a "storm relief event."
Lower Manhattan, which includes Wall Street, was among the hardest-hit areas after the storm sent a nearly 14-foot surge of seawater, a record, coursing over its seawalls and highways and into low-lying streets.
Water cascaded into the gaping, unfinished construction pit at the World Trade Center, and the New York Stock Exchange was closed for a second day, the first time that has happened because of weather since the Blizzard of 1888.
A huge fire destroyed as many as 100 houses in a flooded beachfront neighborhood in Queens on Tuesday, forcing firefighters to undertake daring rescues. Three people were injured.
A downtown hospital, New York University's Tisch, evacuated 200 patients after its backup generator failed. About 20 babies from the neonatal intensive care unit were carried down staircases and were given battery-powered respirators.
A construction crane that collapsed in the high winds on Monday still dangled precariously 74 floors above the streets of midtown Manhattan. And on Staten Island, a tanker ship wound up beached on the shore.
With water standing in two major commuter tunnels and seven subway tunnels under the East River, Mayor Michael Bloomberg said it was unclear when the nation's largest transit system would be rolling again. It shut down Sunday night ahead of the storm.
Joseph Lhota, chairman of the Metropolitan Transportation Authority, said the damage was the worst in the 108-year history of the New York subway.
The saltwater surge inundated subway signals, switches and the electrified third rails, and covered tracks with sludge. Workers began pumping the water out and will ultimately have to walk the hundreds of miles of track to inspect it.
Millions of more fortunate New Yorkers surveyed the damage as dawn broke, their city brought to an extraordinary standstill.
"Oh, Jesus. Oh, no," Faye Schwartz said she looked over her neighborhood in Brooklyn, where cars were scattered like leaves.
Reggie Thomas, a maintenance supervisor at a prison near the overflowing Hudson River, emerged from an overnight shift, a toothbrush in his front pocket, to find his Honda with its windows down and a foot of water inside. The windows automatically go down when the car is submerged to free drivers.
"It's totaled," Thomas said with a shrug. "You would have needed a boat last night."
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.