She'd driven to BWI from her home in Norfolk, Va., to take advantage of the low fares to Jamaica, where she planned to visit relatives. She thought she'd given herself plenty of time to park and get to the Air Jamaica gate for an 8:25 a.m. Wednesday departure. But with record hordes of travelers streaming into BWI every day and work on a major expansion snarling traffic, McLean quickly discovered that she'd been way too optimistic.

On her way to park, she heard a radio report that the airport's $7-a-day satellite lots were clogged with cars. A BWI employee warned her that by the time she found a space in another lot, she could miss her flight. Her best shot, she was told, was to dash over to Airport Fast Park in Linthicum Heights, which offers $12.75-a-day parking and a shuttle to the airport. By the time McLean got there, parked her car and boarded the shuttle, it was 8 a.m., and she was frantic.

"All the spaces are filled," lamented the 23-year-old, her browning banana in her hand. "I would have had to park in another lot."

At 8:10 a.m. -- just 15 minutes before her flight -- the shuttle pulled up in front of the airport. If she raced to her gate, she could still make it. McLean scrambled off the bus and rushed inside, disappearing into the crowded terminal.

There was a time when BWI had no trouble living up to its slogan -- "Easy Come, Easy Go." Launched in 1950 as Friendship International, the 3,200-acre airport was an aviation backwater for decades.

Travelers loved the place, especially in comparison to the Washington area's two other airports, National (now Reagan National) and Dulles International, which were busier and more congested. Even its growth in the 1980s as a hub -- first for the now-defunct Piedmont Airlines and then for USAir -- didn't spoil BWI's reputation as a zip-in, zip-out kind of airport.

But by the time Southwest Airlines arrived in 1993, BWI was poised for a breathtakingly vertical takeoff. The airport's passengers have zoomed from 10.2 million in 1990 to 19.6 million last year. Southwest, BWI's largest carrier, handled 6.7 million passengers in 2000, up from 159,751 in 1993.

With 28 consecutive months of double-digit percentage passenger increases, BWI is the country's fastest-growing airport, according to the Airports Council International. Not even Dulles, the previous title holder, is setting as blistering a pace. And the number of travelers is expected to jump an additional 27 percent in the next decade, assuring significant increases in flight delays, according to Federal Aviation Administration projections.

To keep up with the growth, BWI embarked last month on a massive $1.8 billion expansion that will add 12,000 parking spaces, concourses and moving sidewalks over the next five to six years.

In the long run, airport officials say, the project will make BWI a better, more convenient airport. In the short run, however, it threatens to make a mockery of "Easy Come, Easy Go" just as the summer travel season gets underway.

Even before the expansion work began, some fliers were enduring traffic jams -- some before 7 a.m. on Saturdays -- missed flights and frustrating searches for parking. Now, with construction closing roads and changing BWI's parking layout, passengers from as far away as Pennsylvania and Virginia may find a mess waiting for them when they reach the airport.

Officials say they are trying to keep passengers informed of parking and road closures with updates to BWI's Web site, a toll-free number, radio traffic announcements and visits by airport ambassadors to Anne Arundel, Howard and other surrounding counties. The airport has tried to ease the parking crunch by opening the $4-a-day, 3,400-space Gold Lot after its express-service parking lot was relocated by construction, said Mike West, an associate facilities administrator with the Maryland Aviation Administration.

"It is our largest expansion that we've experienced," West said. "Most large airports are all experiencing growth in air travel and facilities demand. We're experiencing it. We've been trying to keep up as well as try to prepare for the future."

There's a lot riding on the airport's success. BWI is at the epicenter of much of central Maryland's business growth, particularly its emergence as a center for the fiber-optics industry.

In the last five years, the airport has been the driving force behind an explosion of car-rental businesses, hotels, restaurants, high-tech firms and retail centers, including the behemoth Arundel Mills mall, said Neil Shpritz, executive director of the BWI Business Partnership.

Shpritz estimates that the partnership's membership has quintupled since it was formed in 1985 to just under 200 member firms employing 110,000 people. The business district surrounding the airport takes in about 80 square miles and includes hundreds of companies in Anne Arundel, Baltimore and Howard counties, Shpritz said.

Bill Badger, chief executive of the Anne Arundel Economic Development Corp., said the airport has produced more than 9,000 jobs and $1 billion worth of economic activity for the county. The airport itself employs about 10,140 people.

Both he and Shpritz consider BWI's expansion inevitable, given the way its regional presence has grown.

"Certainly with the $1.8 billion investment in the airport, the airport will look radically different than it does today," Badger said.

The construction could cause temporary headaches for travelers, he acknowledged. "I think that's going to challenge the 'Easy Come, Easy Go' reputation for business travelers and citizens alike. I think we're going to have to be patient. When all this construction activity is completed, it will be a more convenient airport."

Some businesses are capitalizing on the airport's growth -- and on its growing pains.

Donald W. Eames, owner of The Airport Shuttle, a Columbia-based shuttle-to-door service, said his business started out with four vans eight years ago and now has 24 vans and 80 drivers. His company now picks up about 2,500 passengers a week at their homes and takes them to BWI. He estimates that it takes his vans 15 to 45 minutes to get to BWI, based on the time of the day. His business has grown exponentially, along with the airport, said Eames, whose round-trip prices range from $21 to $24 for the first person and $5 for each additional person in a group.

"When Southwest came in, it just energized the whole airport -- the other carriers kind of picked up the pace," Eames said. "I think we've become more appealing. In the course of construction, you've got some moments of agony. We're a price value. We're a convenience value. There will be people who choose to park, and others who choose to use our service from home right to the door."

Catherine Dorsey, who lives several miles southeast of the airport in Chartwell, said she'll take a shuttle to the airport when she and her husband fly to California for a vacation in October. Even though she lives close enough to BWI to hear the planes swooping overhead, she has run into parking problems at the airport.

Last year, she and her husband left for a Saturday morning flight at 6:05 a.m, arrived at BWI's blue satellite parking lot 11 minutes later, only to discover that the lot was closed. They tried to go to a lot across the street, but that was closed, too. They waited in a line of cars for one of the lots to open. It wound up taking them 45 minutes to get from the parking lot to their airline gate. They were planning to eat breakfast at the airport before their flight, but all they had time to do was get checked in and get on the plane.

"All of us were sitting in our cars waiting for the other lot to open," said Dorsey, 60. "Some people were really, really angry."

John R. Winston, a frequent flier from Fort Washington, said the traffic into BWI from the Baltimore-Washington Parkway can be terrible, especially if there's an accident. The 45-minute drive from his home in Prince George's County can take up two hours on a bad day.

He has missed flights when he hasn't left early enough. Once, the main entrance to the airport was so jammed that people left their cars to walk the rest of the way to the terminals.

"They'd never make their plane if they didn't," said Winston, who works for the Federal Communications Commission.

But he still prefers BWI over Dulles, both for its convenience and cheap fares. "This airport has enjoyed phenomenal growth," he said. "It's a fantastic success."

Waiting for his flight to Massachusetts in BWI's Concourse B, Bill Lemay said much the same thing. He'd flown to BWI on business -- his first visit to the airport in 16 years. He was impressed by what he found and dismissed the notion that the airport's growth had ruined its user-friendly ambience. To him, Logan International in Boston sets the standard for stressful travel. He described BWI as "nice" by comparison.

"It seems like an easy airport to move around in," said Lemay, 56. "I try to avoid Boston whenever I can. This is a vacation compared to Logan."