More than three centuries ago, the Pilgrims staved off the terrors of the wilderness and gave thanks for a feast.

But the tens of thousands of Boston-area students who will return home this week must face the terrors of the modern world--congested airports, bus terminals, and train stations--before they can re-enact the Thanksgiving day meal.

Travel agents and transportation officials say that this Wednesday will be the worst travel day of the year, approached in congestion only by the Sunday following Thanksgiving.

"Getting into and out of the airport will be crazy," said Lainey Anderson, travel agent for American Express Travel Service. "More people are travelling this year than in previous years, and I don't know why," she said.

"This is the heaviest flight period of the year," said Gregory Flynn, a Passenger Service Supervisor for the Pan Am Shuttle. "The worst time will be between 2:00 and 8:00 p.m. on Wednesday," he said.

Flynn said that all regular Pan Am flights within the United States, as well as flights to Bermuda, were booked solid, and that Pan Am was adding 10-12 additional flights to the Boston-to-New York Shuttle.

This year's Thanksgiving Day airport rush may prove especially hectic since overall passenger volume is already up 10 percent over last year, said Logan Airport Spokesman Dee Clark. She said she expected passenger volume to increase by as much as 25 percent on Wednesday.

"If you really want to avoid the rush, then leave on Thursday morning, or cut a class and leave early on Tuesday," said Paula Musto, a spokesman for Eastern Airlines.

Musto said that Eastern was prepared to accommodate all passengers by using as many additional planes as necessary for the Wednesday shuttle to La Guardia Airport in New York.

Train and bus travel should prove no less crowded.

Paula Costello, spokesman for Massport Authority, said that buses would be most crowded from 2 to 5 p.m., and 7 to 8 p.m.

"This is the busiest time of the year for us," said Bob Thurber, dispatcher for Bonanza Bus Lines.

Officials at Greyhound agreed that traffic would be extremely heavy, but promised to provide as many buses as were needed to accommodate everyone.

Ticket sellers at Amtrak predicted "crowds and crowds and crowds."

"You could try the 4:40 on Wednesday morning, the 6:30 or the 7:25, but after that it's hell," said one Amtrak ticket salesman.

"Basically," said Harvard Travel Service employee Chris Small, "it's going to be a madhouse."