Airports have reopened in the north-eastern US after blizzards caused some 7,000 flights to be cancelled over the busy post-Christmas travel period.
Services have now resumed into and out of New York, Boston and Philadelphia.
But officials warn it could take days to clear the flight backlog for tens of thousands of stranded passengers.
Analysts say the storm and its aftermath could cost the airlines up to $100m (£64m). The blizzards also disrupted rail and road traffic.
The conditions were blamed for a car crash in Maine in which a 59-year-old man died, and for stranding two buses carrying some 50 passengers on a New Jersey motorway.
National rail operator Amtrak - which earlier shut its New York-Boston route - announced a limited resumption of services.
The US National Weather Service says the monster snow storm is the result of a low pressure system which originated off North Carolina.
However, forecasters are now expecting milder weather for the rest of the week, which could help in speeding up the clearing of snow.
'Jigsaw puzzle'
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, forcing thousands of passengers to camp out on floors in terminals.
Overall, nearly 7,000 flights were cancelled on Sunday and Monday.
Although the worst weather is thought to have passed, many flights are still experiencing severe delays because of strong winds and what remains of the snow.
And airline officials warn that it could take days to rebook passengers whose flights were delayed or cancelled.
"Any airline scheduler will tell you it's like playing with a jigsaw puzzle where all the pieces keep changing shape," American Airlines spokesman Ed Martell was quoted as telling the Associated Press.
"In some cases we can't give them a new seat because we don't know."
Sales hit
Six US states - Massachusetts, Maine, Maryland, New Jersey, North Carolina and Virginia - earlier all declared emergencies.
Massachusetts Governor Deval Patrick warned that the storm was "expected to produce widespread heavy snowfall, periods of zero visibility, high winds, power outages, coastal flooding, and beach erosion", AFP reported.
Power had already reportedly been cut to tens of thousands of homes in Rhode Island and Massachusetts.
The New York area received up to 51cm (20in) of snow over the last two days.
A subway train was trapped for seven hours before passengers were rescued.
The southern states of Georgia and South Carolina had their first white Christmas in more than a century.
But Washington DC escaped the blizzard, with only a dusting of snow.
The storm moved to Canada's Atlantic coast early on Monday. Around 27,000 homes in Nova Scotia and 11,000 consumers in the New Brunswick area were reportedly left without power.
The timing of the snowstorm meant disruption for many thousands travelling after Christmas reunions and hampered the start of the shopping sales season and the return to work for many commuters.
