BALTIMORE - The gates swing open, and thousands immediately rush inside. They dart across the landscape like a swarm of blue and white locusts, brashly making themselves at home in a place they don't belong.

They are fans of the New York Yankees, converting Camden Yards into their own version of Yankee Stadium.

Through tomorrow, nearly half the crowd at the home of the Baltimore Orioles will be wearing Yankees hats and jerseys while cheering the visitors. It's not a subtle invasion, either. The invaders sing for the Yankees, jeer the Orioles and give the impression they would prop their feet on the coffee table if one were available.

"We definitely feel it," Yankees manager Joe Girardi said. "It's nice to have your fans travel wherever you go. It's great. You hear the chants."

For many, the approximate 3 1/2-hour drive down I-95 from New York to Camden Yards is a sound economic decision - even if it means staying at a hotel, eating at restaurants and paying ticket-scalper prices to get in the ballpark.

John Trush came from New Jersey with his wife, daughter and her boyfriend to see Monday's afternoon game. Trush paid $150 each for tickets marked at $48 and considered it a bargain.

"It's worth it. I'm in the 10th row behind the Yankees dugout," Trush crowed. "Same ticket at Yankee Stadium is $600, and next year it's going to be $850. So trust me, I'm not complaining about the price here."

The Yankees' official Web site lists the top ticket price this year at $400, but those seats are rarely available on game days.

Next year, when the team moves into a new $1.3 billion ballpark, the Yankees will charge $500 to $2,500 for seats near home plate in the first five to eight rows.

So it seems highly likely that the Yankee Invasion of Camden Yards will continue into 2009 and beyond.

"Why not? The concessions are cheaper here, too. Plus, it costs $18 to park at Yankee Stadium. Here, we left our car at the hotel," Trush said.

It's not only Yankees fans who take to the road. With tickets hard to get at Wrigley Field, Cubs fans make the trek to St. Louis.

Red Sox fans head to New York and Baltimore to watch Boston, which has sold out its last 414 regular-season games at Fenway Park since May 2003.

Two hours before Monday's game at Camden Yards, 22-year-old Rich Nieto and 18-year-old girlfriend Kelly Anderson were positioned at the main entrance of the ballpark. Nieto was gripping a baseball, hoping to get an autograph from one of the Yankees hopping out of a cab.

The couple made the trip from Long Island and intended to spend the night at a hotel before heading back last night.

"It's a chance to get away, plus the tickets are like half price what they are at Yankee Stadium," Nieto said. "I paid $40 each, and they'd be like 80 bucks back home."

And so, the Yankees have all the support they need in the home of one of their AL East rivals.

"It's pretty incredible. It definitely energizes our team," Yankees third baseman Alex Rodriguez said. "We love it. There's no question that the Yankees' universe not only helps the morale, but the intensity."

The Yankees have their supporters in virtually every stadium, even at Fenway Park. But the presence of their fans is most evident in Baltimore, where tickets are readily available for anyone willing to make the drive. Camden Yards used to be filled to capacity with Orioles' supporters, but the fan base has wilted in the wake of 10 straight losing seasons.

Yankees fans are more than willing to fill those empty seats.

Wearing Yankees hats and shirts, Mike and Judy Wood made the trip from Lewisbury, Pa., on Monday to see their first game at Camden Yards.

They bought their tickets at an Orioles Store in York for $57 each.

"Not bad at all," Mike reasoned. "Last game I saw at Yankee Stadium, I paid $200 each." *