At least 40 people have been killed, millions are without power and transport across the north-eastern US has been severely disrupted as storm Sandy heads north for Canada.
In New York City, 18 people have been killed and the public transport system remains closed until further notice.
More than 15,000 flights were cancelled, the flight-tracking website FlightAware estimates.
Earlier, Sandy killed more than 60 people as it hit the Caribbean.
Sandy brought a record storm surge of almost 14ft (4.2m) to central Manhattan, well above the previous record of 10 feet (3m) during Hurricane Donna in 1960, the National Weather Service said.
The storm was causing heavy snowfalls over the Appalachian mountains on Tuesday afternoon. It was expected to turn towards western New York state during the evening before moving into Canada on Wednesday, the forecaster said.
At least eight million homes and businesses are without power because of the storm, says the US Department of Energy.
The New York Stock Exchange says it will re-open on Wednesday after two days' closure, as will the Nasdaq exchange. The last time the stock exchange shut down for two days was in 1888.
New York's subway system sustained the worst damage in its 108-year history, said Joseph Lhota, head of the Metropolitan Transit Authority (MTA).
Subway tunnels were flooded and electrical equipment will have to be cleaned before the network can re-open.
A fire tore through the Breezy Point area of Queens in New York City
New York Mayor Michael Bloomberg said there was "no timeline" for when the subway would restart, but he hoped buses could begin running again on Wednesday.
All New York's major airports are closed as their runways are flooded.
It is likely to be two or three days before power is restored to most of the city, Mr Bloomberg said.
The Path commuter train service, which links New Jersey and New York City, is likely to remain suspended for seven to 10 days, New Jersey Governor Chris Christie told a news conference.
The tidal surge from the storm left fields of debris 7ft (2.25m) high and carried small railway goods cars onto elevated sections of the New Jersey Turnpike, he said.
A large section of Atlantic City's famous boardwalk was destroyed when Sandy slammed into the New Jersey shore
President Barack Obama suspended campaigning for a third day ahead of next week's presidential election so that he could supervise the clean-up.
His Republican challenger Mitt Romney resumed low-key campaigning on Tuesday, converting a rally into a storm relief event in the swing state of Ohio.
Governor Christie, a Republican and staunch supporter of Mr Romney, went out of his way to praise the Democratic president for his handling of the storm.
"I spoke to the president three times yesterday," Mr Christie told CNN. "He's been incredibly supportive and helpful to our state and not once did he bring up the election... If he's not bringing it up, I'm certainly not going to bring it up."
The cost of clearing up after the storm is likely to run to $30-40bn (£18-24bn), says the BBC's business correspondent Mark Gregory - far less than than the $100bn cost of clearing up after Hurricane Katrina in 2005.
In other developments:
US federal agencies in Washington DC will re-open on Wednesday
Fire destroyed about 50 homes in the New York City borough of Queens
More than 200 patients were evacuated from New York University's Tisch Hospital after power went out and a backup generator failed
The oldest nuclear power plant in the US, Oyster Creek in New Jersey, remains on alert due to rising water
President Obama has also declared emergencies in Massachusetts, Connecticut, Rhode Island, New Jersey and Pennsylvania.
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