It's looking like it will be a crowded but profitable holiday season for U.S. airlines.
More than 45 million people are expected to fly around the world on U.S. carriers between Dec. 16 and Jan. 5, according to the trade group Airlines for America. That would represent an increase of 3.5 percent over the same period last year.
To accommodate the growing number of travelers, which has been climbing throughout the year, airlines are adding more flights, larger planes and approximately 99,000 more seats during the holiday period.
"An improving economy and reduced airfares remain the driving force behind the growth seen in air travel," said John Heimlich, vice president and chief economist for Airlines for America.
That means travelers should be prepared for more crowded flights — and potentially long lines. Dec. 22 and Dec. 23. are expected to be the two busiest of the season, according to the group.
But the encouraging news for travelers is that the busy Thanksgiving weekend was relatively problem-free, Heimlich said.
"Airlines' concerted and well-coordinated efforts over Thanksgiving helped ensure the traditional holiday rush was as smooth as could be for fliers, resulting in shorter security wait times and noticeably higher on-time performance rates," he said. "We expect to see much of the same this winter holiday travel season."
Meanwhile, Gary Kelly, chairman and chief executive of Southwest Airlines, gave CNBC his view of the state of the industry heading into the end of the year.
"If the economy in fact continues to grow, oil prices continue to stay low we're going to do really well," Kelly told CNBC on Wednesday.