US and Canada snowstorm causes travel chaos
A winter storm has blanketed parts of Canada and the north-eastern US with up to 2ft (61cm) of snow.
The storm has been blamed for 11 deaths and forced the cancellation of more than 4,000 flights since Wednesday.
With the wind chill, the temperature dropped as low as -29C (-20F) in Toronto and -38C in Quebec City, the lowest seen in two decades.
Authorities warned residents to remain indoors, both for their own safety and to keep roads clear for snow removal.
New York City Mayor Bill de Blasio, who was sworn into office on 1 January, said most of the city's main roads had been cleared of snow thanks to an "extraordinary job" by the city's sanitation workers.
"We can help them by getting out of their way," he said late on Friday morning. "If you do not need to travel today, please stay home."
Some commuter trains around New York City were on a reduced schedule, while some key roads were shut at least temporarily.
In the neighbouring states of Connecticut, Massachusetts and New Jersey, non-essential state workers were ordered to remain at home.
Even as the snow slowed in the eastern US, a coastal flooding alert was in effect for Nantucket in southern Massachusetts through southern Maine, especially for high tide at 12:00 local (17:00 GMT).
The New York to Boston Amtrak passenger rail service was placed on a reduced schedule.
On Friday, Massachusetts Governor Deval Patrick said flights at Boston's Logan International Airport had resumed.
But he warned locals to remain indoors due to "dangerously" low temperatures expected in the region through Saturday.
Crushed by salt
The New York Times said 6in of snow had fallen on Central Park by 07:00 and the temperature was the same as in Fairbanks, Alaska. Friday is forecast to be bitterly cold across much of the region.
Boston too was badly affected, with schools shut.
Eleven deaths have been blamed on the wide-ranging storm, according to the Associated Press news agency.
A salt storage worker was killed in Philadelphia when a 100-ft (30-metre) pile of road salt fell and crushed him. A woman suffering from Alzheimer's disease in New York state froze to death after she wandered away from her rural home.
A man was reported to be in critical condition after being pulled from Lake Michigan by firefighters.
In Canada, parts of Newfoundland and Labrador are expected to see up to 40cm (16in) of snow on Friday, while Nova Scotia is forecast to see as much as 20cm (8in).
The eastern half of the country has been plunged into bitterly cold temperatures over the past several days, making it feel as low as -35C (-31F) with wind chill in the Atlantic Provinces.
David Phillips, a senior climatologist with Environment Canada, told the BBC the temperature in Toronto on Friday morning, -24C, was the coldest the city had seen in nine years. On Thursday, Montreal and Quebec City saw their coldest temperatures in 10 and 21 years respectively.