A traveler holds a dog as she checks in at American Airlines at LaGuardia Airport in New York. Whether it's by rail, bus or roadway, AAA estimates that 42 million people traveled somewhere for Thanksgiving. Cooperative weather and mostly efficient airport operations contributed to smooth traveling conditions.

NEW YORK — Tens of millions of Americans returning home after the long Thanksgiving holiday weekend Sunday had cooperative weather and mostly efficient airport operations to thank for smooth traveling conditions.

Other than a winter storm that is bringing freezing rain and snow to the central Plains Sunday night and flood warnings in northern Texas and Arkansas, weather across much of the country is seasonably mild, said National Weather Service meteorologist Bruce Sullivan.

“Enjoy it while it lasts,” he said.

Most airports across the country were running with delays of 15 minutes or less Sunday night, according to Federal Aviation Administration air traffic control system data. But a large volume of passengers at Seattle-Tacoma International in Washington, Newark International in New Jersey and LaGuardia in New York, led to slightly longer delays, the data show.

In Atlanta, officials are projecting 88,000 travelers to pass through the world’s busiest airport by the end of Sunday, making it their busiest day so far this year. A spokesman for Hartsfield-Jackson International Airport says the previous record for the year was 80,000 people on Columbus Day.

Lobbying group Airlines for America estimated more than 25 million passengers would take to the sky on U.S. airlines during the 12 days surrounding Thanksgiving.

And the motoring group AAA estimated that nearly 47 million Americans were expected to travel at least 50 miles from home via car, plane or bus over the weekend — the highest number since 2007.

At Pennsylvania Station in New York City, college junior Seth Greenspan said the normally chaotic transit hub appeared strangely calm as he awaited an Amtrak train back to the College of William & Mary in Virginia after spending Thanksgiving on Long Island.

“Amtrak itself can be unreliable, whether or not it’s a holiday,” he said ahead of an eight-hour trip. “So far it seems OK.”

Toni Baines and her husband, Marlon, who spent Thanksgiving in the Bronx and were heading back to their home in Richmond, Va., said it appeared transit officials anticipated an influx of travelers and planned accordingly.

“They’ve been running a lot of extra trains,” she said.

“So far we haven’t had any problems.”

Highway patrols and state transit officials across the country advised drivers to budget extra time, particularly during the peak travel hours of 11 a.m. to 3 p.m., in anticipation of heavy volume of cars on the road.