By Brendan O'Brien and Jon Herskovitz
(Reuters) - A swath of the U.S. East Coast from Philadelphia to New York City to Maine was bracing for a potentially historic blizzard on Monday that is 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 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 were already canceling 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 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 was the storm of Feb. 11-12, 2006, that dropped 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 see between 12 to 24 inches (30-60 cm) of snow. The New York City area could be the hardest hit from the storm with lashing winds and snowfall of 30 inches (76 cm) or more in some suburbs.
Delta said on Sunday it was canceling 600 flights because of the blizzard warning for the East Coast. Southwest Airlines said it had canceled about 20 flights and American Airlines had so far canceled a handful.
Cities along the heavily populated East Coast had snowplows and trucks to dispense road salt on standby. Stores have seen a rush of shoppers stocking up on essentials.
"People have been coming in since this morning, buying rock salt and shovels," said Michael Harris, who works at Ace Hardware 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 snowplows, including 12 loader-mounted snowblowers, prepared to deploy, the governor's office said.
The NWS expects as much as 8 inches (20 cm) of snow for western Maryland and southern Pennsylvania, while parts of New Jersey through eastern Massachusetts may get 6 to 12 inches (15-30 cm) of snow by Tuesday morning.
(Reporting by Brendan O'Brien in Milwaukee; Additional reporting by Luc Cohen in New York; Writing by Jon Herskovitz in Austin, Texas; Editing by Jeffrey Benkoe and Peter Cooney)