People used to joke that in the United States, soccer was the sport of the future - and always would be.

When Major League Soccer arose and began a decade-long flirtation with Philadelphia, the joke took on a local dimension: Philadelphia was the once-and-forever expansion team.

Yesterday, the future finally arrived.

MLS commissioner Don Garber made it official during a raucous news conference in Chester, where the new team will play, his words setting off a prolonged ovation from several hundred fans and supporters at a waterfront office complex.

"It took us 12 years to bring the world's most popular sport to the City of Brotherly Love," Garber said. "Today I am proud to officially announce that in 2010, Philadelphia will be joining Major League Soccer as the league's 16th team."

What could have been a two-minute communique from MLS headquarters turned into a 90-minute celebration, with fans, team owners, former players, and league officials hugging one another and shaking hands, sharing a happy disbelief that this day had finally arrived. Children in youth-club jerseys darted past men in business suits, the odd soccer ball dribbled loose, and loud chants went up from the Sons of Ben, the fan group that labored for months to win a team and has about 1,000 members.

"For it to come to this day - amazing," said group president Bryan James, a Sons of Ben scarf across his shoulders and reporters' microphones in his face. "We've been building for it, and building for it."

Twenty-seven years after men's outdoor soccer was last played professionally in Philadelphia, the game is coming back to the city, or at least someplace close - impoverished Chester, 18 miles away.

The team will join a league that after 12 seasons still struggles toward profitability but has made gains in recent years, primarily through the construction of so-called soccer-specific stadiums. The owners insist the team will be successful, on the field and at the gate, avoiding the fate of the Philadelphia Fury, which left town in 1980 to become the Montreal Manic. The Fury were the second North American Soccer League team to fail here, following the Atoms, who folded three years after winning the championship in 1973, their first season.

Two hours before the scheduled announcement, people began streaming into Turbine Hall, a ballroom on an upper floor of the Wharf at Rivertown, owned by the Buccini/Pollin Group, which is part-owner of the new team. American soccer legend Walter Bahr was there, along with a couple of players from the Atoms. So were Gov. Rendell, Senate Majority Leader Dominic Pileggi, other state legislators, Mayor Nutter, Delaware County officials, a string band, and loads of fans who have wanted a team in Philadelphia for a decade.

Flags representing the 14 MLS teams hung overhead, and the sound system blared, "I Just Want to Celebrate." Huge video monitors showed - who else? - David Beckham, MLS's hottest property, scoring goal after goal. It was an afternoon of exultation and reflection.

Nick Sakiewicz, chief executive officer of the ownership group, thanked his wife and children - whom he missed during seven-day workweeks filled with meetings, negotiations, and travel from North Jersey to Chester to New York. Others recalled the Philadelphia ethnic teams of the past, and players who shed sweat and blood for no greater payment than the joy of the game.

How did it feel to secure the new team? "Like it's a dream," said James Nevels, one of the owners and chairman of the Swarthmore Group, an investment company. "And, frankly, like it's a dream come true."

His priority: "Make sure we open this thing in April 2010."

"This thing" is a $115 million waterfront soccer stadium, the anchor for a broader $500 million development of stores, restaurants and townhouses. Revised estimates show the stadium will seat 20,000, about 1,500 more than originally projected.

The team name, logo and colors have not been decided. Officials said the club would be named for Philadelphia, not for Chester or a broader locale, such as Pennsylvania or the Delaware Valley.

Deposits for season tickets are already being accepted at 1-877-MLS-2010 (1-877-657-2010) and www.MLSPhilly2010.com.

Yesterday, a few minutes before 2 p.m., the lights in Turbine Hall went down, leaving only the stage illuminated - like the dusk before the band takes the stage at a concert. Then a hundred members of the Sons of Ben marched in, emerging into the light and shouting like rock stars as they held their blue-and-yellow scarves aloft. The Polish American String Band led a chorus of "I'm Looking Over a Four Leaf Clover," the official SOB song.

"We're going to build a team, a stadium, and we're going to lift some trophies along the way, and have some fun, so get ready," Sakiewicz told the crowd. "The Philadelphia area wanted soccer, and today they got soccer."

It was anything but easy. The local bid survived a winnowing that eliminated several cities and gave the 15th team to Seattle. That left Philadelphia and St. Louis battling for one expansion slot.

MLS insisted the expansion team must have wealthy ownership and a deal to build a soccer stadium. St. Louis organizers locked up a stadium agreement in September, but struggled to attract investors. The Philadelphia group had money but no stadium deal - until last month, when Rendell committed $47 million from the state.

Yesterday, Garber called the Philadelphia bid "the right ownership group, the perfect stadium solution." He gave soccer jerseys emblazoned "MLS Philadelphia 2010" to the owners, who waved them at cheering spectators.

In an interview, he said more good news may be coming Philadelphia's way: New teams playing in new stadiums are typically chosen to host MLS all-star games and championship games, and while nothing has been decided, Philadelphia can expect a similar reward.

Yesterday, speaker after speaker exclaimed that the stadium complex would spark a Chester renaissance, lifting it to the heights of its blue-collar past, when manufacturing jobs employed tens of thousands and the city bustled.

Rendell has portrayed the state investment as a bargain, the ignition for a project that the builders say will create 2,600 construction jobs, 800 permanent jobs, and $19 million in annual tax revenue. Sports economists vigorously dispute such projections, saying stadiums make poor economic drivers and rarely return money to taxpayers. The governor insisted yesterday that the stadium complex would bring untold intangible benefits to Chester, helping it lure development.

"What a day, huh?" Nevels asked the crowd. "What a day for Chester."

Find more stories about Philadelphia's new MLS franchise at http://go.philly.

com/soccerEndText

Contact staff writer Jeff Gammage at 610-313-8110 or jgammage@phillynews.com.