The north-eastern seaboard of the United States is trying to get back to normal after trhe weekend blizzards.
Canada's Atlantic coast was also hit by the storm - the fourth in as many weeks in the region.
Flights have now resumed in and out of New York, Boston and Philadelphia.
But the BBC reports many passengers are expected to be stranded until the end of the week after some 7000 flights were cancelled over the busy holiday travel period.
Forecasters now predict milder weather for the rest of the week.
However, airline industry experts said it would be difficult for companies to accommodate all the stranded passengers in the New York area quickly enough.
Three airports serving New York - JFK, La Guardia and Newark Liberty International Airport - and also Boston's Logan and Philadelphia International reopened on Monday evening. They had been closed since early morning.
Analysts say the storm and its aftermath could cost the airlines up to $US100 million.
The US National Weather Service said the snow storm was the result of a low pressure system which originated off North Carolina.
The BBC reports six states - Massachusetts, Maine, Maryland, New Jersey, North Carolina and Virginia - all declared emergencies earlier.
The New York area received up to 51cm of snow over two days.
The states of Georgia and South Carolina had their first white Christmas in more than a century.
Problems in Canada
The storm moved to Canada's Atlantic coast early on Monday.
Storm warnings have been issued for a 2000km stretch of the Atlantic Coast.
Around 27,000 homes in Nova Scotia have already lost power as fierce wind gusts and blizzard conditions descend on the region.
On Monday, New Brunswick had wind gusts of up to 100km per hour. Around 11,000 consumers in the area are currently without power.
The BBC reports dozens of flights have been cancelled or delayed, particularly in the Toronto area.
