This Thanksgiving will see most Americans heading down the highway instead of leaving on a jet plane.

Though it's traditionally been the busiest travel time of the year, many people  still skittish after the Sept. 11 terrorist attacks are expected to stay put this Thanksgiving holiday, and those who do travel are more likely to drive.

Those who want to take advantage of lower gas prices   under $1 per gallon in some places and who are worried about airline security, are hitting the roads in larger numbers this year. Though air travel will dip by about 15 to 20 percent, the National Highway Safety Board is predicting a 30 percent jump in highway travel.

The AAA estimated that 34.6 million Americans will travel at least 50 miles from home during the holiday, down 6 percent from last year. But a record 87 percent are expected to drive, while the number taking airplanes, trains and buses will drop 27 percent.

"All the indications we're getting is that travel will be down somewhat this Thanksgiving, but it will still be very heavy," said Patrick Hogan, spokesman for the Metropolitan Airports Commission, which operates Minneapolis-St. Paul International and six regional airports in the area.

As the first major holiday to fall after the Sept. 11 attacks, this Thanksgiving will likely be more nerve-wracking for travelers.

Despite the predicted decline in flying, airports are still likely to be jammed, and staff will be under pressure to make tightened security measures go smoothly for tense passengers.

Industry experts said fliers should expect longer lines, more delays and even some flight cancellations. And tensions promise to be running higher than usual, as many people will be taking to the skies for the first time since the attacks.

But some passengers say the events of Sept. 11 aren't going to stop them from flying.

"It's going to be on people's minds," passenger Bob Morin told Fox News, "but you've got to go on with your life."

Among airlines, there's been a push to educate travelers by issuing travel tips in the hopes of cutting down on holiday mayhem caused by the new security procedures.

"There are a lot of things people can do to make [the] travel experience a little easier," said United Airlines spokeswoman Chris Nardella. "United has undertaken a number of initiatives to ensure the safety of our customers."

United has hired up to 2,000 additional security personnel and added a dozen extra checkpoints at hubs and larger airports. Many other airlines have taken similar steps.

Passengers are advised to check the status of their flight before leaving for the airport and to arrive a whopping two hours before departure for domestic flights and three for international.

"It's going to be a new experience for people," Hogan said. "The most important thing they can do is arrive early so they aren't rushed and aren't stressed."

And packing light is more important than ever. For security reasons, passengers will no longer be allowed to carry on two bags. Instead, only one carry-on plus a small item like a briefcase or purse may be taken onto the plane. Two bags per passenger can be checked, and all luggage must have identifying tags including name, address, telephone number, and destination.

Though some have advised against bringing electronic equipment like computers or cell phones, the FAA and airlines say those items are allowed.

Nevertheless, air travelers should expect much closer scrutiny of their belongings. All luggage will likely be searched, and abandoned bags will be seized. Items such as nail scissors, pocket knives and other sharp tools will be confiscated from carry-ons. Canes, crutches or wheelchairs might be inspected, and passengers could even be asked to take off their shoes or watches.

Even though 'tis the start of the gift-giving season, airlines suggest passengers save the wrapping until they arrive at their destination — guards may unwrap suspicious gifts at checkpoints.

Hogan said that though fliers should be prepared for some changes, the scene at most airports isn't going to be that unfamiliar this year.

"It will be busy, there will be lines and it will take time, but I don't think it will be that different from what we've seen in years past," he predicted.

With so many more people on the road this long weekend, motorists are being warned to buckle up and be mindful of other drivers.

Nationwide, more than 10,000 law enforcement agencies are cracking down on child passenger safety, seat belt and drunk driving laws to help make Thanksgiving — traditionally one of the most dangerous travel holidays of the year — a little bit safer.

The Associated Press contributed to this report.