Airports have reopened in the north-eastern United States after blizzards caused about 7,000 flights to be cancelled over the busy post-Christmas travel period.
Services have 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 $US100 million. The blizzards also disrupted rail and road traffic.
National rail operator Amtrak - which earlier shut its New York-Boston route - has 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 expecting milder weather for the rest of the week, which could help in speeding up the clearing of snow.