U.S. airlines expect 45 million passengers to fly between Dec. 17 and Jan. 4, an increase of 2 percent, or 47,000 travelers a day. Last year, 44 million travelers flew during the winter holiday period, the industry group, Airlines for America, said Wednesday.

The busiest day at airports will be Friday Dec. 19. The least crowded days will be Christmas Eve, Christmas Day, New Year's Eve, and New Year's Day, the group said. Airlines will add seats, primarily by flying larger aircraft. Planes are expected to be 80 percent to 90 percent full.

- Linda Loyd