NEW YORK — More than 35 million people along the Philadelphia-to-Boston corridor rushed to get home and settle in Monday as a fearsome storm swirled in with the potential for hurricane-force winds and 1 to 3 feet of snow that could paralyze the Northeast for days.

Snow was blowing sideways with ever-increasing intensity in New York City by midafternoon as flurries began in Boston. Forecasters said the storm would build into a blizzard, and the brunt of it would hit late Monday and into Tuesday.

As the snow got heavier, much of the region rushed to shut down.

More than 6,500 flights in and out of the Northeast were canceled, and many of them may not take off again until Wednesday. Schools and businesses let out early. Government offices closed. Shoppers stocking up on food jammed supermarkets and elbowed one another for what was left. Broadway stages went dark.

“It’s going to be ridiculous out there, frightening,” said postal deliveryman Peter Hovey, standing on a snowy commuter train platform in White Plains, New York.

All too aware that big snowstorms can make or break politicians, governors and mayors moved quickly to declare emergencies and order the shutdown of streets and highways to prevent travelers from getting stranded and to enable plows and emergency vehicles to get through.

“This will most likely be one of the largest blizzards in the history of New York City,” New York City Mayor Bill de Blasio warned. He urged New Yorkers to go home and stay there, adding: “People have to make smart decisions from this point on.”

Up to now, this has been a largely snow-free winter in the urban Northeast. But this storm threatened to make up the difference in a single blow. 

Boston was expected to get 2 to 3 feet of snow, New York 1 1/2 to 2 feet, and Philadelphia more than a foot.

The National Weather Service issued a blizzard warning for a 250-mile swath of the region, meaning heavy, blowing snow and potential whiteout conditions. Forecasters warned that the wind could gust to 75 mph or more along the Massachusetts coast, and up 50 mph farther inland.

New York City’s subways and buses planned to shut down completely by 11 p.m., commuter railroads across the Northeast also announced plans to stop running overnight. Most flights were canceled out of the region’s major airports.

Authorities banned travel on all streets and highways in New York City and Long Island and warned that violators could be fined $300. Even food deliveries were off limits on the streets of takeout-friendly Manhattan. The governors of Massachusetts, Connecticut and Rhode Island also slapped restrictions on nonessential travel.

“We learned the lesson the hard way,” said New York Gov. Andrew Cuomo, referring to instances in which motorists got stranded in the snow for 24 hours or more.

Nicole Coelho, 29, a nanny from Lyndhurst, New Jersey, was preparing to pick up her charges early from school and stocking up on macaroni and cheese, frozen pizzas and milk at a supermarket.

“I’m going to make sure to charge up my cellphone, and I have a good book I haven’t gotten around to reading yet,” she said.

Shopping cart gridlock descended on Fairway, the gourmet grocery on Manhattan’s Upper West Side. The meat shelves were all but bare, customers shoved past each other, and outside on Broadway, the checkout line stretched for a block as the wind and snow picked up. Store employees said it was busier than Christmastime.

“We’re used to these big snowstorms in New England, but 2 to 3 feet all at once and 50 to 60 mph winds? That’s a different story,” said Ben Shickel, 24, who went grocery shopping in Chestnut Hill, Massachusetts, and found shelves had been cleaned out.

In yet another possible sign that people were hunkering down at home, Fresh Direct, a grocery delivery service in the Northeast, said it had seen a rise in orders for “movie-day” snacks such as microwave popcorn and chocolate chip cookies.

On Wall Street, however, the New York Stock Exchange stayed open and said it would operate normally Tuesday as well.

Coastal residents braced for a powerful storm surge and the possibility of damaging flooding and beach erosion, particularly in New Jersey and on Cape Cod in Massachusetts. Officials in New Jersey shore towns warned people to move their cars off the streets and away from the water.

Utility companies across the region put additional crews on standby to deal with anticipated power outages from high winds.

The storm posed one of the biggest tests yet for Massachusetts Gov. Charlie Baker, who has been in office for less than three weeks. He warned residents to prepare for power outages and roads that are “very hard, if not impossible, to navigate.”

The storm interrupted jury selection in the Boston Marathon bombing case and forced a postponement in opening statements in the murder trial of former NFL star Aaron Hernandez in Fall River, Massachusetts.

The Super Bowl-bound New England Patriots got out of town just in time, leaving from Logan Airport around midday for Phoenix, where the temperature will reach the high 60s.

The Washington area was expecting only a couple of inches of snow. But the House postponed votes scheduled for Monday night because lawmakers were having difficulty flying back to the nation’s capital after the weekend.

Associated Press writers Dave Collins and Pat Eaton-Robb in Hartford, Connecticut; David Porter in Lyndhurst,New Jersey; Jim Fitzgerald in White Plains, N.Y.; Bruce Shipkowski in Trenton, New Jersey; Deepti Hajela, Jonathan Lemire and Verena Dobnik in New York; Albert Stumm in Philadelphia; and Marcy Gordon and Darlene Superville in Washington contributed to this report.