Philadelphia is the third stop on United's five-city North American tour. More than 40,000 are expected to attend, and plenty will be wearing red.
"I really like the players, I like the story and the history of the club," said Mike Costa, a 30-year-old Philadelphia lawyer who runs the local branch of One United USA, the U.S. supporters group. "Maybe in some ways I'm a product of that global reach of the team."
For Costa, the turning point in what was a long-distance love affair came when he saw United play live in Philadelphia, at the 2003 exhibition that drew 68,396 to Lincoln Financial Field.
He's going to tonight's game with about 10 friends, all ardent United fans.
David Herman, who helps run One United USA as its "prime minister of public relations," said he won't be traveling to Philadelphia from his home in Chicago but will attend matches in Kansas City and Houston.
The fan group, based in Huntington, N.Y., started as a way for English expats to keep up with their favorite team. Now American-born fans dominate the 250,000 registered supporters, Herman said.
Communications advances from cable TV to the Internet let fans follow their team in real time from almost anywhere. No more waiting for a taped broadcast or the next day's newspaper.
Even at a quarter-million strong, One United constitutes a fraction of the fan base. A study by TNS Sport, now Kantar Sport, estimated United's worldwide fans at 333 million. This year, Forbes magazine ranked United as the most valuable sports club in the world, worth $1.87 billion. The Dallas Cowboys were second.
Walk the Great Wall in China, or the villages of South Africa, and chances are you'll spot someone wearing a United jersey, cap or scarf.
Some of that reflects soccer's standing as the most popular sport in the world, excluding Canada and the United States.
Some of it stems from United's success: More than 40 major titles, including three European championships since 1907-08.
Some of that is due to its stars, a roll call that recently has included Cristiano Ronaldo, David Beckham, and Wayne Rooney.
Some of that comes from its history, both glorious and tragic.
In the 1950s, the "Busby Babes," young stars guided by manager Matt Busby, captured fans' imagination by winning league titles in 1955-56 and 1956-57. In 1958, eight players were killed in the crash of a flight carrying the team. The loss lingers in memory as the Munich air disaster.
The 1960s saw the emergence of Bobby Charlton, who helped England win the World Cup, and striker George Best, known as the "fifth Beatle" for his long hair and playboy ways.
Since 1986, the team has been managed by Sir Alex Ferguson, as much a legend as the players he leads.
When the team travels to Asia, United midfielder Darren Fletcher said in an interview, it's common for fans to stand outside the hotel all day and night.
"Grown men and women, crying in the streets when your bus comes by," said Fletcher, captain of Scotland's national team.
Veteran United goalkeeper Edwin van der Sar, who starred for Holland's national team, said he continues to be amazed by the interest.
"People at the airports, hotels. Security people who are there to guard us, but [who] get into the elevator and pull out a shirt to sign."
Where doesn't that happen? One place: the United States. And this week, in Philadelphia. During a Monday media session, only a few fans stood outside the team's Center City hotel, and they departed soon after the players arrived.
"You wouldn't think the biggest team in the world is here," Van der Sar said.
United's tour began with training sessions in Chicago, followed by a July 16 win over Scottish power Celtic FC in Toronto. United plays Major League Soccer's Kansas City Wizards in Kansas City on July 25 and serves as the opponent at the MLS all-star game in Houston on July 28.
On July 30, United takes on Chivas Guadalajara in Mexico, though that game is not part of the official tour.
Wardle, the Octagon executive, and a fan of rival West Bromwich Albion, said several factors draw teams like United to play here.
For one, overseas tours can be lucrative. United, like other English clubs, has carried considerable debt, much of it incurred during the purchase by the American Glazer family, which also owns the NFL Tampa Bay Buccaneers.
Another reason to tour, Wardle said, is United knows it must increase interest in the United States if it's to be a truly worldwide brand.
"They work hard at being a global franchise. They go to China, they go to Japan, they go to South America. Yes, they are collecting significant appearance fees, but it's really an exercise in brand-building. They commit to different parts of the world on a rotating basis."
That has a direct impact on the club's popularity and income.
A couple of years ago, Wardle said, he was in Cape Town and went to the Nike store to buy a South Africa jersey. To his dismay, he found the store carried exactly three shirts:
Manchester United red. Manchester United white. And Manchester United black.
Contact staff writer Jeff Gammage at 215-854-2415 or firstname.lastname@example.org.