NEW YORK — Millions of East Coast commuters returned to work today over slick roads and icy sidewalks after a weekend winter storm dropped record snowfall, interrupted holiday shopping and stranded travelers.

The storm crept up the coast on Saturday and Sunday, walloping states from the mid-Atlantic to New England, causing hundreds of delayed or canceled flights, widespread power outages and treacherous driving conditions. The weather was blamed for at least seven deaths, including a snowmobile driver who crashed head-on into a horse-drawn buggy in Pennsylvania’s Amish country.

Meanwhile, airports in the Northeast that were jammed up this weekend were working their way back to normal. The Federal Aviation Administration today was reporting that all major airports on the East Coast had average flight delays of less than 15 minutes.

Still, three major airports in the New York City area were expecting an unusually busy holiday travel week as many who were stranded by the cancellation of 1,200 flights over the weekend try to make it to their destinations.

Despite the storm’s powerful punch, many took solace in the fact that the timing could have been worse, even if it left people trapped in their homes all weekend.

Thomas Standers, of New Rochelle, N.Y., was feeding dozens of Christmas cards into a mailbox at the train station in Pelham early today.

“If we hadn’t been stuck inside all weekend, these would never have gotten done,” he said. “Now we have a fighting chance they’ll get there by Christmas.”

Many schools and offices were closed today, making traffic a little lighter on slow-moving roads and lessening the strain on beleaguered transit systems. Highways were largely clear, but secondary roads remained treacherous.

In Washington, federal agencies were closed today and bus service was running behind schedule, but the Metro finally was able to open all 86 of its rail stations. Subways had been limited to underground stations for two days.

Joy Ricasa, 59, a bookkeeper, said she drove from her home in Upper Marlboro, Md., to the Largo Metro station early today to commute into Washington. The roads were “coated with ice,” she said.

“I was very careful. I don’t want to have an accident,” Ricasa said.

In New York City, the Long Island Rail Road urged its riders to allow extra time; several passengers said the ride itself was fine, but getting to the train was a problem.

“The roads are a mess,” loan officer Sophia White, 42, said this morning after she took the train from Queens to Manhattan, enroute to Jersey City, N.J. “The plow truck came through but it’s very icy still.”

J. Silhan worked an overnight shift at the Gurney’s Inn oceanfront resort in Montauk, N.Y., after spending all day Sunday plowing and digging out people’s houses with his father-in-law.

“I’ve been up 24 hours,” Silhan said this morning. “I’m going to go crash” — hastily emphasizing that he meant “sleep.”

Commuters also found it slow going in Philadelphia, where many residential streets were still snow-covered and the Southeastern Pennsylvania Transportation Authority suspended service on some bus routes.

Even as some workers returned to the job today, their children were being given the day off.

Philadelphia’s public and Roman Catholic schools were closed to give the city another day to clear streets and sidewalks. Schools also were closed Monday in Baltimore, Roanoke, Va., most of Washington’s suburbs and many Long Island towns, among other areas. Washington, D.C., public schools were already scheduled to be on winter break today.

On the rails, Amtrak canceled some trains in the East today because of the storm and warned that long-distance trains to the South and West faced substantial delays.

Power outages remained an issue. More than 130,000 people were without power in West Virginia and Virginia as of this morning.

The storm came on the last weekend before Christmas, and merchants feared they’d take a hit as the storm blew through, shutting people indoors.

Crowds were unusually light Sunday morning at the Providence Place mall in downtown Providence, where Reuben Tillman III, a salesman at Champs Sports, said he had made only one sale in his first couple of hours at work.

“But I do have a theory: Everybody who’s here has a SUV,” he said. “This is happy truck day.”

Tillman predicted that business would be booming closer to Christmas, with people who opted to stay home on Sunday doing last-minute shopping on Tuesday and Wednesday.

The storm yielded record snowfall totals at several locations. The 16 inches recorded Saturday at Reagan National Airport outside Washington was the most ever for a December day. Philadelphia, which recorded 23.2 inches, had its second-largest snowfall since it began keeping records in 1884.

The storm began wreaking misery Friday in South Florida, where it caused flooding and knocked out electricity in the Carolinas before turning to snow as it moved north.

Four people were killed in accidents on snow-covered roads in Ohio, Virginia and West Virginia.

Another death in Virginia is believed to have been caused by exposure, and authorities there said the weather may have contributed to another traffic death.

In Pennsylvania, a 20-year-old man was killed Saturday afternoon when the snowmobile he was driving crashed head-on into a horse-drawn buggy. The two people in the buggy were unhurt.

In western North Carolina, a man was killed when his car slid down an embankment.

A plow truck driver was found dead in his truck with the motor running Sunday on New York’s Long Island, but it was unclear whether his death was related to the storm, police said.

Black ice will be a concern tonight after sunshine and “a little bit of melting,” said Richard Castro, of the Weather Service in Upton, N.Y.