When the Seahawks’ potential move to California was put to a referendum, an unlikely voting bloc helped keep the team in Seattle

This is the story the loudest crowd in the NFL probably doesn’t want you to know. It is the story of how the Seattle Seahawks nearly disappeared, how the best home-field advantage in professional football almost never happened and how it took a passionate band of soccer fans to save football in Seattle.

On Sunday the Seahawks will host the NFC Championship Game in an attempt to reach their second straight Super Bowl. CenturyLink Field will again be sold out and the 68,000 fans crammed into its stands will try to rattle the Green Bay Packers as they do most opponents who find communications impossible in the face of a roar that has literally triggered seismic events. Flags with the number 12 will flap throughout the city anointing the crowd as an extra, essential 12th man in Seattle blue.

Yet there was a time not that long ago when the Seahawks were not adored in their home city, when the team played before huge swaths of empty metal bleachers and a fleet of moving vans hauled the team’s equipment to California in the first stage of a move to suburban Los Angeles. That was in 1996 and the Seahawks’ presumed departure did not generate much protest. Several losing seasons had been further blemished by a series of off-field troubles and the team’s owner, Ken Behring, was despised as an outsider determined to whisk the Seahawks away.

Hoping to keep the team in Seattle, Microsoft co-founder Paul Allen offered to buy the Seahawks but with one caveat: he wanted a new stadium to replace the dreary Kingdome, he wanted $300m of public money to help finance it and he wanted the financing to be approved in a statewide referendum that Allen would pay to hold. If the vote failed, Allen vowed to walk away, returning the Seahawks to Behring who appeared ready to complete the team’s California move.

Winning the election seemed an almost impossible task. Allen’s request came as the city’s baseball team, the Mariners, was prevailing in an ugly fight for a new stadium. The Mariners were far better liked at the time than the Seahawks and few in the state of Washington wished to give Allen — then the world’s seventh-richest man — tax money for a stadium. As the June 1997 vote drew near the Seahawks supporters were desperate for a miracle.

Then Fred Mendoza called Allen’s offices.

Mendoza is a Seattle attorney and soccer fan who by the mid-1990s was playing on a handful of adult teams, coaching his children’s teams and providing legal advice to a local soccer organization. The MLS had just started, giving America its first true major soccer league since the folding of the NASL in the 1980s and the people in Mendoza’s circle longed for a Seattle team. But the MLS did not want a franchise in the Kingdome and efforts to build a soccer-only stadium went nowhere.

One day Mendoza read a newspaper story about Allen’s struggles to get funding for a football stadium and he was hit with a thought. “I immediately went ‘Whoa, football has a rectangular stadium and that would be perfect for a soccer field,’” Mendoza recalls.

He phoned Allen’s offices and left a message. The next day he found himself sitting in the office of Bert Kolde, one of Allen’s top advisors who was helping to run the stadium effort. He told Kolde there were some 300,000 people involved in soccer around Seattle, many of them dearly wanted an MLS team and if the proposed football stadium could be marketed as a football and soccer stadium … well there might be more than a few votes in it.

“This is exciting,” Mendoza remembers Kolde saying.

Allen’s people scrambled to turn their football project into a combined football and soccer stadium. They hired an architect with soccer expertise to redraw the stadium’s blueprints, widening the corners to accommodate a soccer field, moving lights so they would illuminate the sidelines and slightly raising the lowest rows of the grandstand to give better soccer sightlines. Mendoza drove around the state with Kolde and Seahawks president Bob Whitsitt, attempting to woo skeptical newspaper editorial boards. Several times he went to the state capitol to beg legislators for their support.

But his biggest work was done on the weekends, when he set up a tent at youth soccer games. He had a microphone and a sound system and he told the people who gathered around him that Allen was committed to helping Seattle get a soccer team.

“Fifty, 60, 70 people would come over and listen and they would say: ‘Hey let’s get the stadium,’” Mendoza says.

The Sounders have become known for their passionate fanbase. Photograph: Ted S Warren/AP

A key moment came in the spring of 1997 when MLS commissioner Doug Logan and NFL commissioner Paul Tagliabue attended a city luncheon in support of the stadium. After the lunch, Logan said: “You have our assurances that Major League Soccer will be here if the stadium is built.”

Suddenly Seattle’s soccer community had something tangible: a guarantee. People who hated the idea of helping to fund a stadium for Allen were campaigning to have it built.

“Knowing what I know about soccer today [the fans] brought a totally different demographic to the vote,” says Gary Wright, a Seahawks vice president at the time who was later instrumental in starting the Sounders MLS franchise. “The hardcore soccer person isn’t the same as the hardcore football person. It widened the margins of the electorate by bringing in extra people.”

As the referendum drew near, support for the stadium grew. On election day, more than 1.6 million people cast ballots in a vote so close the result wasn’t known until the next morning. Eventually word came: the stadium had passed by a mere 36,780 votes, a margin of 51% to 49%.

“There is no question the soccer vote was the difference,” Mendoza says. “And Paul will tell you that. Without soccer there would be no Seahawks today.”

Five years later, the stadium opened with a gigantic half-roof designed to capture crowd noise and direct it toward the field. Soon the stadium became known as the loudest building in the NFL, an obvious home advantage for the Seahawks who then won a string of NFC West championships. The team so scorned in the mid-1990s that locals often called it “the Seachickens” became the most-beloved sports team in the city. The near-move to California was forgotten.

But there is also this. The MLS team Seattle finally got in 2009 has turned into the league’s most valuable franchise. For all five years of the Seattle Sounders existence the team has led the MLS in attendance, averaging more than 43,000 the last three seasons, a figure that would put it in the top half of all the European leagues.

“The Sounders themselves were shocked by it,” says local radio broadcaster Mike Gastineau whose book — Sounders FC Authentic Masterpiece — describes the unprecedented rise of Seattle’s soccer franchise. “All their projections said they would draw 16,000 to 20,000 a night and do a little better than break even. It turns out they were in the right place at the right time.”

And yet none of the Sounders success would have happened without the Seahawks. For it turns out Logan’s promise in 1997 meant little in the MLS offices. It took 10 years for Seattle to get its soccer team and another two before the team played a game — an eternity for many soccer fans started to wonder if they had been duped, especially when a promised grass field (necessary in international soccer matches) was replaced by FieldTurf at the Seahawks request.

Eventually Allen had to invest in a portion of the expansion franchise and enlist the help of Seahawks employees to operate it before the MLS granted Seattle a team.

Few of those Sounders fans will be in the stands on Sunday. Wright says there is little crossover between the soccer and football crowds. The Sounders have been marketed to young people in their 20s working for tech companies and living downtown. The Seahawks have a more established, more suburban base.

No one at CenturyLink Field will be thinking about soccer as the Seahawks play for another Super Bowl. But if someone was to look close Sunday afternoon, they would see the faint, mostly-erased lines the Sounders soccer pitch peeking from beneath the hash marks ...

A subtle reminder of the sport that saved the Seattle Seahawks when they were all but gone.