Air, road and rail travel across the nation could soon return to pre-Sept. 11, 2001, levels for the first time, powered by a summer season that begins today and could reach record levels despite all-time-high gas prices and heightened terror warnings, tourism officials say.

Large numbers of Americans are finally comfortable enough with their fears and their bank accounts to set aside concerns about terrorism, the economy and the war in Iraq -- if only for a long weekend -- and have some adventure and relaxation, the officials say.

Air travel is up almost 5 percent for the first few months of 2004 compared with last year, and April travel was up 10 percent over 2003, the Travel Industry Association of America said. That trend was reflected at Reagan National Airport, where parking lots were full in March for the first time since early 2001, and at Baltimore-Washington International Airport, which has experienced double-digit increases in passengers this year.

Amtrak officials said ridership is up 6.4 percent this year, and the rail service reported 2.2 million passengers in April, the highest number for that month in its 32-year history. Industry analysts predict that hotel occupancy rates this summer will be at their highest since 2000.

Lon Anderson, a spokesman for AAA Mid-Atlantic, said more than a half-million Washington area residents will take off for beaches, mountains and elsewhere this weekend, a 3 percent rise from last year, according to a survey done for AAA. About 85 percent of them will hit the highways, he said, brushing aside gas prices that have climbed past $2 a gallon and raising the possibility of hours-long traffic jams today.

"Basically, people said they're leaving. They're going out of town in hordes," Anderson said. "If you're not on the road by noon . . . you're going to have a lot of trouble."

Many of them also will be heading into town, with tomorrow's dedication of the National World War II Memorial on the Mall.

The airports could be jammed. An increase in the number of fliers has caused problems at area airports, where hundreds more flights are planned for this summer. National Airport's 7,500 parking spaces are filling up, a situation expected to get worse when 22 new daily flights start taking off in June, officials there said.

Dulles International Airport has been troubled with flight delays, partly because one of its three runways is closed for repairs until mid-August. Delays there could worsen next month, when several hundred flights will be added to the daily schedule.

"We're back at both of our airports to pre-September 11 numbers, and we're pleased to see passengers returning," said Tara Hamilton, a spokeswoman for the Washington Metropolitan Airports Authority. "But it does present a lot of challenges for airport operators."

Hamilton advised travelers to take taxis or Metro to National and to leave extra time to circle lots if they have to drive. She also said people should get to airports at least two hours before takeoff, especially on heavily traveled weekends such as this one.

Concerns about getting through security lines have accelerated along with the expected traffic, particularly since summer travelers often include children, senior citizens and others who are not familiar with the mark-your-laptops, take-your-shoes-off rules and procedures of the post-Sept. 11 world.

To try to head off major problems, the Transportation Security Administration held news conferences at Dulles and 42 other airports this week to offer tips for passengers. Among them: Don't wear big metal belt buckles, and don't bring wrapped presents with carry-on luggage.

Airline experts said that, in addition to passengers' rising comfort level with flying, an increase in service by low-cost carriers is generating more traffic in the area.

Independence Air, a new regional carrier based at Dulles, will launch next month with about 600 takeoffs and landings by the end of the summer. Frontier Airlines, Jet Blue, Al Italia and Ted, a low-fare subsidiary of United Airlines, have expanded service at Dulles, officials said.

Those carriers should help return passenger traffic at Dulles close to the 20 million mark this year, about where it was in 2000 before it reached a low of 16.9 million last year, officials said.

Similarly, traffic at National is expected to rebound to an average of 15 million passengers this year, after dropping as low as 12.9 million in 2002.

BWI officials said the airport reached pre-Sept. 11 levels last year and has experienced double-digit increases in travel since then.

"This year the attitude is, 'I'm going, and that's it,' " said Terry Trippler, president of the travel Web site terrytrippler.com. "We'd seen the planet before September 11, and we got hooked. It just took us a while to get back."

Still, on holiday weekends such as Memorial Day, most people simply hit the road. You don't have to tell Carl Lebo, a dentist from Rockville who is going to extremes to minimize time spent in the car (with whiny children) and maximize time spent on the beach (with sun and ocean breezes). Lebo has given his four-person office the day off today so he and his family can drive to their house in Bethany Beach, Del., early this morning instead of fighting traffic later in the day.

"It takes the pressure off," Lebo said. "It makes the entire trip more pleasant, and you get a whole extra day." A 21/2-hour drive instead of the five-hour "horror story" he has suffered in the past also cuts down considerably on the complaining from his 13-year-old and 11-year-old, he noted.

To make sure anxiety about traffic doesn't spoil any of the weekend, Lebo said, the family will return early Tuesday instead of with the masses Monday.

Luggage-hauling Metro riders appear to be getting an early start to the long weekend at the National Airport stop.