Holiday travelers make their way through busy Hartsfield-Jackson

If you weren’t among the millions hitting the roads or taking to the air this long holiday weekend, that’s probably something for which you were thankful.

Sunday, considered the last day of the long Thanksgiving holiday weekend, is expected to be one of the busiest times to travel.

At Hartsfield-Jackson International Airport, for instance, an estimated 300,000 passengers are expected to pass through.

The Transportation Security Administration “continues to keep all lanes open and fully staffed to move passengers along quickly,” according to a statement from airport officials. “We encourage passengers to arrive two hours before their scheduled departure time for domestic flights and three hours before their scheduled departure time for international flights and to check with their airline for updates to their flight status.”

Passengers can go online to check wait times.

While the weather was clear in metro Atlanta, there were spots of inclement winter weather elsewhere in the nation, which has forced some airlines to delay flights that could have an impact here at the world’s busiest airport.

Delta, JetBlue and American are among airlines that issued travel waivers for those who want to cancel or change their plans.

Airport officials advise passengers to check with their airlines prior to their arrival.

» RELATED: AJC's guide to the airport this holiday season, including parking and security

Although the Wednesday before Thanksgiving is usually pretty hectic, Sunday is no slouch.

Final numbers aren't in, but the industry group Airlines for America said the busiest day of the year in history for U.S. airlines could be Dec. 1.

During the holiday period, more than 55 million travelers were expected to take a trip of 50 miles or more away from home this Thanksgiving, making this the second-highest Thanksgiving travel volume since AAA began tracking in 2000.

The record was set in 2005, according to AAA, the Auto Club Group.

Overall, an additional 1.6 million people will travel compared with last year, a 2.9 percent increase, with most travelers opting to drive. The increase is most likely due to a stronger economy, higher wages in some sectors and increased disposable income, AAA said.

If you're among those on the highway, Gas Buddy's Sunday report showed Atlanta's gas prices at an average of $2.48 are cheaper than the national average of $2.59.