PHILADELPHIA - A swirling storm clobbered parts of the mid-Atlantic and the urban Northeast on Tuesday, dumping a foot or more of snow, grounding thousands of flights, closing government offices in the nation’s capital and making a mess of the evening commute.

The storm stretched 1,000 miles between Kentucky and Massachusetts but hit especially hard along the heavily populated Interstate 95 corridor between Philadelphia and Boston, creating a perilous ride home for millions of motorists.

The National Weather Service said Manalapan, N.J., got 15 inches of snow by 10:30 p.m. CDT.

Parts of New York City had 10 inches. Near Philadelphia’s airport there was 15.

The snow came down harder and faster than many people expected. A blizzard warning was posted for parts of Massachusetts, including Cape Cod.

Late in the afternoon, highways in the New York City metropolitan area were jammed, and blowing snow tripled or even quadrupled drive times.

“I just want to get to the Bronx,” motorist Peter Neuwens lamented. “It’s a big place. Why can’t I get there?”

New York Mayor Bill de Blasio urged residents to avoid driving, in part to keep roadways clear for city workers. The city put 450 salt-spreaders on the streets and had 2,200 other vehicles on hand to tackle any storm emergencies, he said.

De Blasio also announced stepped-up efforts to reach out to the city’s most vulnerable, including increased efforts for the homeless. And he urged neighbors to look out for one another.

“Just be careful about any kind of exposure in this kind of weather,” he said.

New York Gov. Andrew Cuomo, New Jersey Gov. Chris Christie and Delaware Gov. Jack Markell declared states of emergency to deal with the storm.

Some travelers, suddenly stranded in New York, hoped to get hotel rooms, though lodging was increasingly difficult to find.

“Usually we get lots of cancellations,” said Evelyn Peralta, who takes reservations at the boutique hotel POD 51. “But this time, even with the cancellations, it doesn’t meet the new incoming reservations.”

In Jersey City, N.J., Stanley Gaines, wearing just a thin jacket and huddling beneath an overhang as snow stung his face, said he had been stuck for more than an hour waiting for a ride home from his appointment at a Veterans Affairs clinic.

“I’m waiting on anything I can get: a taxi, a shuttle, a bus,” Gaines said, squinting to read the destination on an approaching bus in near whiteout conditions. “I didn’t really pay attention to the weather this morning because there was no snow on the ground, and now - this!”

Pennsylvania’s Transportation Department said Tuesday that it had already gone through more than half of its$189 million winter weather budget.

“Lots of nuisance storms this season have meant that PennDOT crews have been plowing and treating roads more frequently this winter,” spokesman Erin Waters-Trasatt said.

The storm was a conventional one that developed off the coast and moved its way up the Eastern Seaboard, pulling in cold air from the Arctic. Unlike the freeze of two weeks ago, it was not caused by a kink in the polar vortex, the winds that circulate around the North Pole.

About 3,000 flights were canceled by Tuesday evening, with airports from Washington, D.C., to Boston affected. More than 1,000 flights for today were called off, as well. Amtrak planned to cut back train service in the afternoon.

Forecasters said the storm could drop up to 14 inches of snow on Philadelphia and southern New England and up to a foot on New York City, to be followed by bitter cold as arctic air from Canada streams in.

As of Tuesday night, there was mostly light snow across Connecticut, Rhode Island and eastern Massachusetts from the Boston area southward.

The weather prompted Massachusetts Gov. Deval Patrick to postpone Tuesday night’s State of the State address.

In Maryland, 8 inches had accumulated in Westminster, and at least 7 inches had fallen in Frederick. The storm was blamed for at least one death in Maryland after a car fishtailed into the path of a tractor-trailer rig on a snow-covered road about 50 miles northwest of Baltimore.

Schools in Pennsylvania, New Jersey, Connecticut, Virginia, West Virginia and Kentucky stayed closed for an extra day after the Martin Luther King Jr. Day holiday, or sent students home early. Some parents kept their kids home all day, unwilling to put them on slippery roads for a few hours of school.

Federal workers in the Washington, D.C., area were also given the day off. Washington was expected to get 4-8 inches of snow.

Washington Mayor Vincent Gray said the steady snowfall that had developed by midday Tuesday vindicated his decision to close schools and government offices.

“I suspect that this morning there were people who questioned the decisions that we made,” Gray said. “But I think as we look at the conditions outside now, hopefully it is clear that it was the right decision to make.”

Standing in Philadelphia’s Love Park with snow swirling around her, visitor Jenn Byrne of Portland, Ore., said the nasty weather put a crimp in her plans to do a “giant walking tour” of the city. But she vowed to soldier on, taking cabs instead of trudging. She wasn’t wearing snow boots.

“I’ll keep going. Just the means of transportation will change a bit,” Byrne said.

Others shrugged off the snow, as well.

In Herndon, Va., where citizens were casting ballots in a special election that was likely to determine control of the state Senate, Earlene Coleman said she felt obligated to make her selection. “It only made sense to come out and do my duty.”

Construction worker Tony Cockrell, stopping for coffee at a Hagerstown, Md., gas station, said he planned to continue driving to work sites in western Maryland and northern Virginia to supervise the installation of insulation in building projects.

“If you don’t work, you don’t get paid,” he said, adding that deep cold is good for business. “We’re trying to get stuff insulated so it doesn’t freeze up.”

Meanwhile, the cold weather also affected states farther south.

Tennessee Gov. Bill Haslam on Tuesday declared a state of emergency to lift restrictions on the transportation of propane as subfreezing temperatures hit the state.

Normally, drivers transporting hazardous materials like propane are limited in the number of hours they are allowed to work at a stretch. The state of emergency will allow drivers to work longer hours in the hopes of ensuring propane delivery to homes and businesses during the cold spell.

Snow was forecast for areas east of Interstate 24, with the greatest accumulations expected in the mountains of east Tennessee.

Snowfall already had been reported Tuesday in parts of north Georgia. Forecasters said temperatures in the region were expected to drop to 10-15 degrees, with wind-chill values of zero degrees to 10 degrees below zero. Wind chill is a calculation that describes the combined effect of the wind and cold temperatures on exposed skin.

Snow and ice also hit eastern Missouri on Tuesday. Several accidents were reported. With temperatures in the teens and winds gusting above 30 mph, clearing roadways was difficult.

Southbound Interstate 55 was closed in south St. Louis after a tanker truck collided with a snowplow, causing fuel to leak from the tanker. It wasn’t immediately clear when the interstate would reopen. Accidents also snarled traffic on Interstates 44, 64 and 70 in the St. Louis area.

The utility company Ameren Missouri reported about 5,900 power failures, mostly in the St. Louis area and the Missouri boot heel.

The northern tier of Missouri was under a wind-chill advisory from the National Weather Service. Temperatures in the single digits were combining with strong winds to create a wind chill of minus-15 degrees or colder in an area mostly north of U.S. 36.

Temperatures have changed wildly in much of the state since the start of the year. A storm Jan. 5 was followed by days of bitter cold before temperatures rose quickly into the 50s. St. Louis reached 50 degrees Monday afternoon. Tuesday’s high was expected to be more than 30 degrees colder.

Information for this article was contributed by Kathy Matheson, Michael Rubinkam, Jim Fitzgerald, Samantha Henry, Matt Moore, David Dishneau, Matthew Barakat, Jessica Gresko and staff members of The Associated Press; by Marc Santora of The New York Times; by Brian K. Sullivan, Jim Polson, Naureen S. Malik, Esme E. Deprez, Anna Shiryaevskaya and Annie Linskey of Bloomberg News; and by Ashley Halsey III and staff members of The Washington Post.

Front Section, Pages 1 on 01/22/2014