NEW YORK — Subways started rolling in much of New York City on Thursday for the first time since Superstorm Sandy crippled the nation’s largest transit system. Traffic crawled over bridges, where police enforced mandatory carpooling.
Subway platforms were not crowded. Only a dozen people waited on a platform at Penn Station, and in Brooklyn, an F train headed toward a bus stop in near silence, with a fraction of its normal passenger load.
Trains in Manhattan ran only north of 34th Street, unable to travel through flooded tunnels in downtown Manhattan and Brooklyn.
New Yorkers were grateful anyway. Ronnie Abraham, a technology worker, was waiting at Penn Station for a train to Harlem, a trip that takes 20 minutes by subway and 2½ hours on city buses that have been overwhelmed since resuming service Tuesday.
‘‘It’s the lifeline of the city,’’ Abraham said. ‘‘It can’t get much better than this.’’
After reopening airports, theaters and the stock exchange, city officials hoped the subway would ease the gridlock that had paralyzed the city, forcing cars and pedestrians to inch through crowded streets without working stoplights.
Television footage Thursday showed heavy traffic coming into Manhattan as police turned away cars that carried fewer than three people, a rule meant to ease congestion.
Flights took off and landed Thursday at LaGuardia Airport, the last of the three major New York-area airports to reopen since the storm, which killed more than 70 people across the Northeast and left millions without power.
Across the region, people stricken by the storm pulled together, providing comfort to those left homeless and offering hot showers and electrical outlets for charging cellphones to those without power.
The spirit of can-do partnership extended to politicians, who at least made the appearance of putting their differences aside to focus together on Sandy.
‘‘We are here for you,’’ President Barack Obama said Wednesday in Brigantine, N.J., touring a ravaged shore. ‘‘We are not going to tolerate red tape. We are not going to tolerate bureaucracy.’’
Obama joined Republican Gov. Chris Christie, who had been one of the most vocal supporters of Republican presidential hopeful Mitt Romney, to tour the ravaged coast. But the two men spoke only of helping those harmed by the storm.
On Wednesday, masses of people walked shoulder-to-shoulder across the Brooklyn Bridge to Manhattan for work, reversing the escape scenes from the Sept. 11 terror attack and the blackout of 2003.
They reached an island where many people took the lack of power and water and transportation as a personal challenge.
On Third Avenue, people gathered around a power strip that had been offered to charge cellphones.
At a fire hydrant on West 16th Street, 9-year-old Shiyin Ge and her brother, 12-year-old Shiyuan Ge, stood in line to fill up buckets of water. But unlike the adults, the two kids held plastic Halloween candy pails painted with grinning jack-o-lanterns.
‘‘There’s no water in our house,’’ said Shiyin Ge, who had planned to dress up as a ladybug for Halloween.
Downtown Manhattan, which includes the financial district, Sept. 11 memorial and other tourist sites, was still mostly an urban landscape of shuttered bodegas and boarded-up restaurants. People roamed in search of food, power and a hot shower.
Suburban commuter trains started running for the first time on Wednesday, and Amtrak’s Northeast Corridor was to take commuters from city to city on Friday for the first time since the storm.
From West Virginia to the Jersey Shore, the storm’s damage was still being felt, and seen.
In New Jersey, signs of the good life that had defined wealthy shorefront enclaves like Bayhead and Mantoloking lay scattered and broken: $3,000 barbecue grills buried beneath the sand and hot tubs cracked and filled with seawater.
Nearly all the homes were seriously damaged, and many had disappeared.
‘‘This,’’ said Harry Typaldos, who owns the Grenville Inn in Mantoloking, ‘‘I just can’t comprehend.’’
Most of the state’s mass transit systems remained shut down, leaving hundreds of thousands of commuters braving clogged highways and quarter-mile lines at gas stations.
Atlantic City’s casinos remained closed. Christie postponed Halloween until Monday, saying trick-or-treating wasn’t safe in towns with flooded and darkened streets, fallen trees and downed power lines.
Farther north in Hoboken, just across the Hudson River from Manhattan, nearly 20,000 people remained stranded in their homes, amid accusations that officials have been slow to deliver food and water.
One man blew up an air mattress and floated to City Hall, demanding to know why supplies hadn’t gotten out. At least one-fourth of the city’s residents were flooded, and 90 percent were without power.
The outages forced many gas stations across the state to close, resulting in long lines of people looking to fuel cars and backup generators. Darryl Jameson of Toms River waited more than hour to get fuel.
‘‘The messed-up part is these people who are blocking the roadway as they try to cut in line,’’ he said. ‘‘No one likes waiting, man, but it’s something you have to do.’’
On New York’s Long Island, bulldozers scooped sand off streets and tow trucks hauled away destroyed cars while people tried to find a way to their homes to restart their lives.
Richard and Joanne Kalb used a rowboat to reach their home in Mastic Beach, filled with 3 feet of water. Richard Kalb posted a sign on a telephone pole, asking drivers to slow down: ‘‘Slow please no wake.’’
Five-foot snow drifts piled up in West Virginia, where the former Hurricane Sandy merged with two winter weather systems as it went inland. Snow collapsed parts of an apartment complex, a grocery store, a hardwood plant and three homes.
The sixth person killed in the state was a candidate for the state House, John Rose Sr., who was struck by a falling tree limb. His name will remain on the ballot on Election Day.
A few more inches might fall in West Virginia, but meteorologists said the remnants of the storm are in the Appalachian Mountains and will be gone by the end of the week.
Contributing to this report were Verena Dobnik, Eileen AJ Connelly, Karen Matthews, David B. Caruso, Leanne Italie and Lou Ferrara in New York; Samantha Henry in Hoboken, N.J.; Wayne Parry in Mantoloking, N.J., Katie Zezima in Seaside Heights, N.J.; Frank Eltman in Mastic Beach, N.Y., Larry Neumeister in Long Beach, N.Y., and Vicki Smith in Elkins, W.Va.