It came despite grim projections of power and mass transit outages lasting several more days.
With six days to go before next Tuesday's elections, President Barack Obama will visit storm-ravaged areas of the New Jersey shore, where Sandy made landfall on Monday.
His guide will be Republican Governor Chris Christie, a vocal backer of presidential challenger Mitt Romney who has nevertheless praised Obama and the federal response to the storm.
Sandy, which has killed at least 50 people in the US, pushed inland and dumped snow in the Appalachian Mountains. Its remains slowed over Pennsylvania, and it was expected to move north toward western New York and Canada, the National Weather Service said.
Blizzard warnings and coastal flood warnings for the shores of the Great Lakes were in effect.
Battered by a record storm surge of nearly 14ft of water, swaths of New York City remained submerged under several feet of water. In the city's borough of Staten Island, police used helicopters to pluck stranded residents from rooftops.
Across the Hudson River in Hoboken, New Jersey, members of the National Guard arrived to help residents pump floodwater from their homes.
More than 8.2million homes and businesses remained without electricity across several states as trees toppled by fierce winds tore down power lines.
In New Jersey, Governor Christie said it could take seven to 10 days before power is restored statewide.
UK airlines were hoping to resume flights to and from storm-lashed New York later today.
British Airways had to axe most of its services to New York and neighbouring Newark this morning, but hopes it will be able to get flights away later today to both cities.
It will be the first time since Sunday afternoon that BA has been able to operate to New York and Newark due to the storm.
Virgin Atlantic, whose services have also been disrupted, is also hoping to fly to the two cities later today.
In the lower half of Manhattan, 250,000 people remained without power after a transformer explosion at a Con Edison substation on Monday.
On Manhattan's Lower East Side, one of the neighborhoods without power, 87-year-old Thea Lucas said she came outside from her apartment, where she lives alone, to warm herself up with a walk and to feed seven cats that she looks after.
"I can make hot water," she said. "But there is no heating and I'm all cold inside."
Despite much of the city's financial district being damaged by flooding, financial markets were scheduled to reopen today as well.
How much activity could take place remained to be seen, however, as many workers may be unlikely to get to work without subways and commuter railroads from the suburbs.
On Broadway, the Theater League announced that most shows would resume performances today. Shows had been cancelled since Sunday due to the storm.
Sandy also forced New York City to postpone its traditional Halloween parade, which had been set for tonight in Greenwich Village.
