But there will be a 6.7 percent decrease in the number of air travelers, totaling 2.3 million this year, continuing a decade-long decline of Thanksgiving air travel.
In the report released Wednesday, AAA officials said the expected increase reflects improved consumer confidence from a year ago, when Thanksgiving travel dropped 25 percent following the country's housing and economic problems. Americans may feel more financially secure and be more willing to travel, the report says.
"The economy is still very clearly weighing heavily on the minds of Thanksgiving travelers this year, and that's evidenced by the very small increase that we expect to see in total travel," said Geoff Sundstrom, a spokesman for AAA's national office in Heathrow, Fla.
However, the slight increase suggests the economy has slightly stabilized, he said.
Blanca Enriquez, 59, of El Paso, Texas, said she's driving more than 800 miles to South Padre Island with her family for Thanksgiving.
"We couldn't fly because I've got too many grandkids, so it's better to take a road trip," Enriquez said. "We've been saving since the summer, otherwise it would not be possible."
The Air Transport Association has predicted that holiday passenger traffic will drop 4 percent from last year, despite airlines' heavy discounting in the past several months. With fewer flights, planes are likely to be full over Thanksgiving, the trade group said.
Travelers began checking in for holiday flights Saturday at Reagan National Airport in Washington, D.C. College student Lucy Crowley, 22, said she booked her flight to leave several days before the holiday.
"I made travel plans around avoiding that rush," she said.
Crowley said two of her roommates from California will join her family in Boston, because tickets are cheaper there than going home.
Tammy Jones, a spokeswoman with the Federal Aviation Administration, said the agency will work with the Defense Department to allow commercial air traffic to use air space normally reserved for the military - as it's done the past few years - in the Southwest, East Coast and West Coast.
AAA forecasts about 2.9 million people will take other modes of transport, including trains and buses. That's up about 1.2 percent from last year.
Amtrak expects Wednesday to be its heaviest single travel day of the year, with as many as 125,000 passengers nationwide.
The rail system is bracing for the holiday by running more trains with higher capacity on its lines in the Pacific Northwest, Chicago area and the Northeast corridor. Most of those will run on the busiest days - the day before Thanksgiving, and the Sunday after.
Dwayne Houston, 37, a federal contractor from Landover, Md., said he plans to take an Amtrak train to Charlotte, N.C., on Wednesday and then drive his elderly father and stepmother to visit relatives near Orlando, Fla. He said air travel was too expensive.
"For the both of them it was not in their budget, it was going to cost them about $400 or $500 ... to save the money they decided to drive," Houston said.
Others are staying put. Tami Howlett, 41, a teacher from Tulsa, Okla., said as a single mother with two kids she decided to spend Thanksgiving at home to save money.
"We're just trying to keep it limited and save money for the summer," Howlett said. "You just have to appreciate what you have."