NEW YORK Mon Jan 26, 2015 2:26am GMT

A swath of the U.S. East Coast from Philadelphia to New York City to Maine braced for a potentially historic blizzard on Monday expected to dump as much as 3 feet (90 cm) of snow and snarl transportation for tens of millions of people.

The National Weather Service (NWS) on Sunday issued a blizzard warning for the northern section of the East Coast from Monday afternoon until Tuesday, placing states from New Jersey to Indiana under winter storm watches and advisories. Airlines canceled hundreds of flights ahead of the storm.

"This could be the biggest snowstorm in the history of this city," New York Mayor Bill de Blasio told a news conference, saying the snowfall could reach up to 3 feet.

De Blasio told residents of America's financial capital and most populous city to stay off the roads and to "prepare for something worse than we have seen before."

The biggest snowfall on record in New York City came during the storm of Feb. 11-12, 2006, dropping 26.9 inches (68 cm), according to the city's Office of Emergency Management.

The NWS called the approaching system a "crippling and potentially historic blizzard," with many areas along the East Coast expected to be blanketed by 12 inches to 24 inches (30-60 cm) of snow. The New York City area could be the hardest hit, with lashing winds and snowfall of 30 inches (76 cm) or more in some suburbs.

Delta Air Lines said on Sunday it was canceling 600 flights because of the blizzard warning for the East Coast, while United Airlines will cancel all Tuesday flights at airports in New York, Boston and Philadelphia. The carrier will limit operations beginning on Monday night at Newark, LaGuardia and John F. Kennedy airports in the New York area, a spokeswoman said.

Southwest Airlines said Sunday evening it would cancel more than 130 of 3,410 flights scheduled for Monday due to the storm, an increase from its earlier plan to cancel about 20 flights.

American Airlines said cancellation plans would not be finalized until Monday morning but that it expected "quite a few" flights to be affected. Flight-tracking website Flightaware.com showed 637 flights canceled for Monday as of Sunday evening.

Cities along the heavily populated East Coast had snow plows and trucks on standby to dispense road salt. Shoppers emptied out many stores, stocking up on essentials.

"People have been coming in since this morning, buying rock salt and shovels," said Michael Harris, who works at the Ace Hardware store in Wading River, New York.

The Philadelphia Streets Department said on its Facebook page that crews were preparing for a "messy Monday morning commute." The Pennsylvania Department of Transportation told travelers to postpone travel if necessary and carry emergency kits if they do go out.

The Connecticut Department of Transportation will have its entire fleet of snow plows, including 12 loader-mounted snowblowers, prepared to deploy, the governor's office said.