Potential owners of a Northern Virginia baseball team, enthusiastic state and county officials and developers came together near Dulles International Airport yesterday to tout Loudoun County as a perfect site for a major league team.

Gathering at Virginia's Center for Innovative Technology, they brought out blue pennants, spouted demographic data showing the Dulles area's wealth and potential for growth and tossed about baseball metaphors.

Just over a stand of trees is a 450-acre site that would be home to a stadium, a large residential and commercial development and, proponents hope, a flooded quarry to be dubbed Diamond Lake.

"Northern Virginia is major league, in every sense of the word," said William Collins, head of a business group that hopes to own a baseball team in Virginia. He added that if his partners succeed in luring the Montreal Expos to Loudoun, the commonwealth would finally get a team with Virginia in its name.

"It's the return of Major League Baseball to the national capital region. But it's in Virginia. That's where the future is."

Major League Baseball officials had pushed Virginia baseball backers to search for a site in Arlington, which would be closer to the capital region's core, but opposition from local officials blocked those efforts, Collins said. Yesterday marked the public unveiling of the Virginia group's latest bid, and the pitch was clear: The wealthy and fast-growing Dulles area is not a lackluster consolation destination.

"It's not another stadium being dropped into an inner-city site that hopefully, perhaps, maybe will lead to redevelopment nearby. Nor is it in the middle of nowhere, that hopefully, perhaps, maybe will lead to new development," said Laurence E. Bensignor, chairman of Diamond Lake Associates, a partnership of home builders behind plans to develop thousands of homes and 5 million square feet of commercial space and help underwrite stadium construction. "It's where it's at already," Bensignor said.

Loudoun's status as the country's fastest-growing county was promoted yesterday as a key selling point to baseball owners. "It's Major League Baseball's only choice," said Bruce E. Tulloch (R-Potomac), vice chairman of the Loudoun County Board of Supervisors.

And to those who see a Dulles stadium as too long a slog from a more iconic or exciting destination in Washington, Collins responded that they're missing the point.

"The reality is you need to be where the fans are and where the businesses are," Collins said. "It is demographics that have driven this entire proposal to Major League Baseball."

John MacDonald, a 13-year-old Babe Ruth player from the western Loudoun town of Purcellville, enthusiastically donned two Dulles Baseball hats over his team cap. As his uniformed buddies giggled and popped lime green balloons, MacDonald cut to the core of why he'd like to see a hometown team.

"You don't have to drive to Baltimore," MacDonald said. "Instead of having to root for a team out-of-state, you could root for a team in your state."

Just how much a Dulles team would sap revenue from the Baltimore Orioles, a fear of O's owner Peter G. Angelos, remains uncertain.

Organizers handed out maps yesterday showing that an estimated 1.5 million people would live within an hour's drive, at rush hour, of the proposed Loudoun stadium in 2008, when it would open, and the vast majority of them would live in the commonwealth. That analysis came in response to questions from Major League Baseball. Supporters said it should placate Angelos, who has opposed relocating the Expos to the region.

"It should make Peter Angelos happy," said James E. Curren, vice president of transportation consultant Transcore.

"Different people are willing to spend more time than others. Most people would probably drive an hour. We drive that for everything else," Curren said. "If you're coming from Montgomery County during rush hour, it's over an hour. If you're coming on Saturday afternoon, obviously it's not."

Angelos could not be reached for comment.

The potential impact on Northern Virginia's clogged roads remained unclear. Curren's analysis showed that a typical 40-minute commute at 5:30 p.m. from Tysons Corner to Ashburn along the Dulles Toll Road would increase by two to four minutes on a game night, he said. The key congestion challenge, he said, is having enough entrances to the stadium to keep fans' cars from plugging roads outside the development.

Project developers have pledged tens of millions in road improvements, including a new interchange with the Dulles Toll Road, an interchange at what is now Innovation Drive and Route 28, and a link between the stadium and the Dulles Greenway. A Smart Tag, an electronic card similar to the EZPass, could be used to pay parking fees to streamline entrance to the park, the developers said. A shuttle service from a Metro station could serve as a stopgap pending a planned Metro extension to Dulles, they said.

Virginia's boosters distributed apple pie to kids in jerseys, and fliers to emphasize perceived shortcomings in the District's rival stadium proposal, which relies on new business taxes to fund a downtown ballpark.

"A Pennsylvania Avenue address, when it comes to baseball, doesn't amount to a hill of beans, because that's not where the people are," said Gabe Paul Jr., executive director of the Virginia Baseball Stadium Authority. "This is where the fan base is."

Staff writer Tom Heath contributed to this report

Fans show support at a rally and news conference detailing plans to bring Major League Baseball to the Dulles area of Loudoun County. Reston residents Matthew Thomas, front, his brother Michael and their mother, Jeanette, show support.