More than 3,000 flights were cancelled on Monday as a fresh winter storm dumped snow, sleet and freezing rain across the northeastern United States.
The worst affected airports are Chicago O'Hare International, Newark in New Jersey, New York's LaGuardia and Boston Logan International, according to tracking website flightaware.com.
The National Weather Service said a strong storm system would bring widespread snow from the Great Lakes region to the northeastern state of Maine with between six and 12 inches (15 and 30 centimeters) expected.
The northeastern city of Boston declared a snow emergency and closed schools.
In New York, America's largest city of eight million, commuters were warned to expect travel delays.