"Motorists will receive a holiday bonus in the form of lower gas prices which are at their lowest levels for the holiday since 2010," said AAA Chief Operating Officer Marshall L. Doney in a statement.
That's expected to help push median spending for holiday travelers down 6.6 percent, from $498 last year to $465 this year, even though the average trip is expected to increase from 588 to 601 miles this year.
(Read more: Holiday getaways: Not too late for deals)
The roads will also likely attract price-sensitive travelers who are balking at airfares that are, on average, 8 percent higher than a year ago, according to Travelocity—or finding out that there are no seats available at any price.
"In a small markets like ours, if you're trying to get back on Sunday, Dec. 1, just forget it," said Randy Moore, owner of Travel Unlimited in Columbia, S. C.
Part of the reason, says Moore, is that smart travelers have come to accept that Thanksgiving travel will always be expensive and are less likely to procrastinate in the hopes of getting a good deal.
"I have clients that start looking the moment flights are in the computer," he said. "They know seats are at a premium and they get their tickets 11 months in advance."
(Read more: Airline carry-on madness escalates during holidays)
They'll have plenty of company over the holiday with load factors expected to top 85 percent on the busiest days, according to the industry trade group Airlines for America. Strong demand, says the group, has prompted carriers to increase capacity by 2 percent over a year ago, but flights on all but the more obscure routes will likely be completely full.
All told, Airlines for America expects 25 million people to take to the skies between Nov. 22 and Dec. 3, an increase of 1.5 percent over last year. To no one's surprise, the busiest day is expected to be Sunday, Dec. 1 (2.56 million passengers), followed by Wednesday, Nov. 27 (2.42 million) and Monday, Dec. 2 (2.36 million).
In fact, according to a new study also released Wednesday by the U.S. Travel Association, such numbers could become the norm even for non-holiday travelers. According to the group, the combination of growing demand and inadequate infrastructure funding means that Thanksgiving-like passenger congestion will be a year-round reality at nearly all of the top 50 U.S. airports within the decade.
In the meantime, says the group, travelers at some airports are already feeling the squeeze. Among the report's findings, several airports, including JFK in New York City, Orlando, Chicago Midway and McCarran in Las Vegas, now experience passenger levels equivalent to the Wednesday before Thanksgiving once a week and an additional 20 will within five years.
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None of which is likely to make traveling this Thanksgiving any more relaxing. At this point, those who have procrastinated will find themselves paying top dollar for airfare, opting to hit the road or rails instead or forgoing holiday travel entirely.
"I just had someone call me and say, 'I need to look at a trip for Thanksgiving,'" said Moore, "and I had to ask him if he was considering Thanksgiving 2014."
—By NBC News contributor Rob Lovitt.
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