Millions of Americans faced the daunting task of digging out from under mountains of snow yesterday as a massive two-day winter storm that had stretched 3,000 kilometres 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 35 centimetres of snow that was being blown into drifts by a bitter Arctic wind that swept in behind the storm.

United Airlines suspended all its traffic at Chicago’s O’Hare hub until 10 a.m. yesterday and warnedof 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 scale. Blizzard, winter storm, freezing rain and wind chill warnings were issued for more than 30 of the 50 US states.

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 3.05 meters in some areas, with snowfalls between 25 and 69 cm in Illinois, Indiana, Wisconsin, Michigan, Minnesota, Oklahoma, Kansas, Massachusetts and New York.

In Chicago – hit by 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 on Wednesday and announced businesses would remain shuttered yesterday.

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

New York City was coated with more than 1.3 cm of it, turning sidewalks into skating rinks. Melting sun later brought the ice crashing onto pedestrians.

“I was walking under a tree, and chunks of ice 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 today.

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. But there were signs of improvement.

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