Super Bowl XLV: Pittsburgh Steelers v Green Bay Packers

• Green party: The 'cheesehead' supporters of the Green Bay Packers are famed for their fanaticism with the legacy of legendary coach Vince Lombardi Photograph: Getty Images

YOU don't have to be a native of Wisconsin to root for the Green Bay Packers in Super Bowl XLV. You don't have to know your Curly Lambeau from your Vince Lombardi to hope that their legacy is honoured in tonight's showdown with the Pittsburgh Steelers. You don't even need to wear a triangle of cheese on your head to know that a victory for the old dairy-farming community will satisfy the game's purists.

More than 100,000 spectators, 5,000 accredited media and millions of TV viewers worldwide will watch this evening's match at Cowboys Stadium, Texas, between two of the NFL's most venerable institutions. And, if there is any justice in the world, any frustration that American football, like numerous other sports, is increasingly driven by only a few filthy-rich oligarchs, its biggest prize will be won by a franchise that continues to swim against the tide.

The Green Bay packers are an anomaly. As the power in professional sport becomes ever-more concentrated in the hands of a few profit-driven investors, the Packers cling faithfully to the belief that they can be run by the fans, for the fans, without sacrificing their lifelong prominence in American football. The second-oldest franchise in the NFL is the last vestige of American sport as it was in the 1920s, an old-fashioned, small-town team who refuse to believe that the key to success is held only by a multi-millionaire owner.

It wasn't such a big deal when they won the Superbowl in 1967, 1968 or even 1996 but, in an era when money talks so loudly that the traditionalists are effectively drowned out, the Packers are justifiably proud of their reputation as the only publicly-owned, not-for-profit organisation in the major leagues of any American sport. About 110,000 people, mainly fans, own the company. Each is limited to 200,000 shares, about four per cent of the total. Although it contravenes NFL rules, which demand that the principal owner has at least a 30 per cent stake in any franchise, the Packers policy was "grandfathered" by the game's governing body in the 1980s.

No individual can assume control of the Packers. If the franchise is sold, the profits must go to charity. It means that, while other teams can be shunted from coast to coast in a shameless attempt to follow the money, Green Bay will forever remain on the shores of Lake Michigan. Those who have shares are entitled to no dividends, no season-ticket privileges, nothing except the joy of part-owning arguably the most storied franchise in NFL history. And boy do they enjoy it, which is what, more than anything, makes the Packers a special phenomenon. There are plenty of fan-run clubs in professional sport - in football alone, the spectrum covers everything from Barcelona to Stirling Albion - but few are quite so able to take on the financial giants with the help only of a small, local population. The people of Green Bay, or "cheeseheads" as they are affectionately known, are remarkably loyal to their team.

Without the Packers, and the monument that is Lambeau Field (named after Earl "Curly" Lambeau, who founded them in 1919), Green Bay would be just another example of small-town America, a few traffic lights swinging in the breeze and the odd flicker of neon outside a deserted sports bar. With a population of little more than 100,000, it is by far the smallest city in America to host a major sporting franchise. A bit like Augusta, a truck-stop town that plays host to the Masters golf tournament, it is something of a sporting Mecca.

A capacity crowd of nearly 73,000 packs into their bowl-shaped, retro stadium for every home match.The last time they failed to sell out Lambeau Field was 1962. More than 70,000 names are on the list for season tickets but, with an estimated wait of nearly a century, the best bet is for one to be passed down in the form of an heirloom.

All of which has an emotional effect on the team. "The level of pride that the fans have for the Packers, and for the Packers players, is unbelievable," says their running back, Ryan Grant, who is in his fourth year with the franchise. "They talk about how proud they are of the type of character the players have, and they're so aware of the different things the players might do in the community.

"The fact that we are a public team, the town really feels like it's their team, and we're a representation of that. We have to be."

That the Packers have remained competitive in the face of modern commercial pressure is thanks also to the way American sport is run, with salary caps, draft picks and revenue-sharing arrangements. There will be no repeat of their halcyon days of the 1960s, when Lombardi, their legendary coach, won them back-to-back Superbowls, but, with the help of their general manager, Ted Thompson, they have used the system to their advantage.

Thompson has gradually assembled a successful young team with a combination of late-round draft picks, undrafted free agents and one or two unpopular decisions, not least of which was his refusal to bring back Brett Favre, their iconic quarterback, when he emerged from retirement in 2008. Despite pressure from angry Packers fans, to whom Favre was nothing less than a God, Thompson stood by his plan to build the team around Aaron Rodgers, the quarterback who will call the shots in Dallas this evening.

For Thompson, it will be a thrilling climax to an injury-plagued season in which his work has been at its most resourceful.

"The fact that he's been able to cut and paste a championship team together, considering all the players they lost, is remarkable," says Ron Wolf, one of his predecessors in the position. "These days you just don't see that."

Pittsburgh are a powerhouse of the modern game with six Super Bowl titles - all of them since 1974 - but with the Packers' wide receiver, Greg Jennings, almost unplayable when he gathers momentum, and BJ Raji, their 24-stone nose tackle, anxious to demonstrate why they call him The Freezer in affectionate remembrance of the Chicago Bears' legendary big man William "The Refrigerator" Perry, tonight's game is too close to call.

Green Bay, it's safe to say, will pack a punch, even if their biggest strength is off the pitch.