Major winter storm sweeps across US and Canada
Authorities closed major highways across the mid-west and warned most roadways in Chicago were impassable
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A bitter winter storm stretching 2,000 miles (3,200km) is crippling swathes of the US and Canada with heavy snow, rain and high winds.
At least 10 deaths were blamed on the storm, including a New York man fatally burned trying to light cooking fuel.
More than 20in (51cm) of snow fell on Chicago, bringing the typically bustling city to a frozen halt.
Southern Ontario in Canada seemed to have escaped the worst of the storm, with 15 to 20cm of snow accumulating.
Environment Canada had predicted the storm would drop 30cm on the province.
More snow was forecast for Canada's Maritime provinces overnight into Thursday.
'Risk of death'
President Barack Obama was briefed on the storm at the White House by emergency management aides including Homeland Security Secretary Janet Napolitano.
The White House said workers with the Federal Emergency Management had been deployed to 13 states to help co-ordinate relief efforts.
Chicago closed public schools for the first time in 12 years More than 6,300 US flights were cancelled, according to tracking website FlightAware.com, including 939 from Chicago's O'Hare International Airport and 341 from New York's LaGuardia.
Illinois state police said much of the state's road system was impassable, and around Chicago, authorities closed major interstate highways and the area's commuter rail system.
The National Weather Service warned of "zero visibility" and bluntly warned Americans in at least four states: "Do not travel."
"Ask yourself if getting to your destination is worth risking your life," the official US government weather information service advised Chicagoans.
Forecasters said the storm would hit the mid-Atlantic or north-east regions late on Wednesday before heading to Nova Scotia in Canada's Maritime provinces.
"The storm has produced blizzard conditions with snow and blowing snow across the Central Plains. Total snowfall accumulations of one to two feet of snow are expected for a large swathe of the central and north-eastern states," the service advised.
Heavy freezing rain was expected south and east of the snow area, the service said.
In Toronto, more schools were closed for snow than for any storm since 1999, CBC news reported.
Ribbons of ice
An estimated 375,000 customers up and down the US and into Canada were without electricity on Wednesday.
Officials have warned that rescue crews may not be able to reach stranded motorists The storm has turned roads into ribbons of ice, stretching the resources of emergency responders to rescue stranded motorists.
In Missouri, the authorities closed the state's entire 250-mile stretch of Interstate 70 between St Louis and Kansas City.
Meteorologist Jeff Johnson of the National Weather Service in Iowa told Associated Press news agency the storm was sure to "cripple transportation for a couple of days".
Oklahoma City and Tulsa, Oklahoma, were paralysed as the storm reduced visibility on the roads and snow piled in drifts as high as 4ft.
The Tulsa World newspaper announced that it would be unable to publish on Wednesday for the first time in its 105-year history.
The series of storms that has hit the US this winter is also wreaking havoc with government budgets. Clean-up costs are placing pressure on already tight public funds.
But other businesses are benefiting, with concerned residents stocking up on essentials.
Plans continued in Dallas, Texas, for Sunday's Super Bowl between the Green Bay Packers and the Pittsburgh Steelers - two teams accustomed to playing US football in adverse wintry conditions.