CHICAGO, Feb 3: Millions of Americans faced the daunting task of digging out from under mountains of snow on Thursday as a massive two-day winter storm that had stretched 2,000 miles made its way off the East Coast.

The storm — one of the largest since the 1950s — had ground travel to a halt, and authorities warned that road conditions remained treacherous.

“Motorists should still not travel if it can be avoided,” said Colonel Ron Replogle, of the Missouri State Highway Patrol as he announced the reopening of Interstate 70, which had been closed all day from one end of the state to the other.

“Also, remember that many other roads around the state are still not passable.” Chicago's O'Hare Airport was struggling to clear the 20 inches of snow that was being blown into drifts by a bitter Arctic wind that swept in behind the storm.

United Airlines has suspended all of its traffic at Chicago's O'Hare hub until 10:00 am (1500 GMT) on Thursday and warns of a slow resumption of flights after that.

State officials were investigating seven deaths possibly linked to the storm, including a man stuck in his car who was dead by the time rescuers arrived and another who suffered a heart attack shovelling snow.

The storm, which stretched from Texas to Maine, was epic in scope.

Blizzard, winter storm, freezing rain and wind chill warnings had been issued for more than 30 of the 50 US states.

FLIGHTS CANCELLED: In all, more than 13,000 flights were cancelled across the country over two days.

States of emergency were declared in Illinois, Indiana, Missouri and Oklahoma and the National Guard was called out to help rescue stranded motorists.

Snow drifts topped 10 feet in some areas with snowfalls between 10 and 27 inches in Illinois, Indiana, Wisconsin, Michigan, Minnesota, Oklahoma, Kansas, Massachusetts, and New York.

In Chicago — hit near-hurricane force winds that sucked more moisture off Lake Michigan — firefighters used snowmobiles to navigate the streets.“It's amazing — it's such a huge city and it's silent,” said school teacher Elana Hiller, as she waded through hip-deep snow along Chicago's lakeshore.

“It's like heaven out here. Everything is white and fresh and quiet.”Despite being known for scoffing at the wintry weather that cripples other cities, Chicago declared its first snow day in 12 years Wednesday and announced they would remain shuttered on Thursday.

Where there was less snow, there was ice, lots of it.

New York City as coated with more than a half inch (1.3 cm) of it, turning sidewalks into skating rinks. Melting sun later brought the ice crashing onto pedestrians.

“I was walking underneath a tree, and bits of ice chunks were falling,” Amelia Priddis, a Londoner on holiday told The New York Times. “You can't dodge

it. You just have to hope it doesn't hit you hard.” Hundreds of thousands of people were left without power in Illinois, Ohio and Indiana after strong winds knocked down power lines, with utilities not promising power to parts of Ohio until late on Friday.

Texas was forced to seek help from Mexico's state electricity company after rolling power outages due to the unusually cold temperatures. An energy transfer of 280 megawatts began at midday via northern Mexican border cities.

Another layer of danger loomed, as a blast of frigid air from Canada followed the storm.—AFP