The majority, about 35.5 million people, are expected to travel by automobile, with the remaining 9.7 million going by airplane, train or bus, Valuet said.
The projections are based on a nationwide survey of 1,500 adults by the Travel Industry Association, which conducts special research for AAA.
"This is the highest figure we've ever seen for any of the holidays," she said.
Luckily for travelers, the record high number will be spread out over the whole period rather than concentrated on just a few days, as it is at Thanksgiving, said Valuet and Tri-State police officials.
Still, travelers should expect Christmas Eve and the Sundays following Christmas and New Year's Day to be very busy, they said.
More than two million people are expected to travel the Pennsylvania Turnpike between noon Dec. 23 and Jan. 3, according to a press release from the Pennsylvania Turnpike Commission.
State police officials in Maryland, West Virginia and Pennsylvania said troopers will be very visible to holiday travelers and will look for drunken, reckless and aggressive drivers, as well as those violating seat belt laws.
Amtrak is expecting about 1.25 million riders between last weekend and Jan. 4 or 5, said spokesman Steven Taub, in Washington, D.C.
Travelers can pick up the Capitol Limited - which runs between Chicago and Washington, D.C. - at the Martinsburg or Harpers Ferry, W.Va., stations, Taub said.
But they can't buy their tickets there, he said.
They can buy them through a travel agent, over the phone, online at the company's Web site and at any manned station, the closest is Union Station in Washington, D.C., Taub said.
About the same number of passengers are expected to ride Greyhound Lines buses during that period, said spokeswoman Katherine Williams, in Dallas.
Greyhound buses will run on their regular schedule to and from the Hagerstown terminal throughout the holiday season, including Christmas and New Year's, said area manager John Maher, in Richmond, Va.
Riders can buy tickets during terminal hours or, if it's closed, pay the bus driver to get on and buy a ticket at the next open terminal, Maher said.
Holiday travelers don't have to worry because the number of buses running on a schedule are increased to handle demand, he said.
Air travelers could save a lot of time and hassle by flying out of Hagerstown Regional Airport, said Barry Waggy, station manager for US Airways Express/Chautauqua Airlines.
Parking is free. It doesn't have the long lines the metro airports do. And, if you have your ticket already, you only have to get there 45 minutes in advance, Waggy said.
Historically, many holiday travelers haven't taken advantage of the airport, he said.
Despite the addition of service to Newark, N.J., this year, Waggy said he expects it will be the same because the bulk of the airport's customers are business travelers.
Traffic tends to be fairly slow from Christmas Eve through the Sunday after New Year's, he said.
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