The icy storm that battered the Southeast on Wednesday shifted into the Northeast on Thursday, taking aim at airports from Charlotte north through New England.
Total cancellations within, into or out of the U.S. topped 6,250 at 2:15 p.m. Eastern time, adding to the more than 3,400 that were scrubbed Wednesday, according to flight-tracking service FlightAware
In Washington, both Reagan National and Dulles suspended all flight operations early Thursday morning. Reagan is a hub for US Airways, Dulles for United.
Delta scrubbed 1,200 flights out of Atlanta Thursday morning but hoped to resume limited operations in mid-afternoon, according to a spokesman.
Amtrak is running reduced services on the Acela and Northeast regional trains between Boston and Washington.
Airlines have waived cancellation and change fees for travel through Feb. 18.