Seattle and Portland have long traded jibes on the quality of their brew pubs and the hipster rating of their music scenes, but the biggest rivalry is now between their football teams.

Football is often considered a niche sport in North America, a late arrival on the sporting landscape that has yet to challenge the historical hegemony of American football and baseball – at least until you arrive in the Pacific Northwest.

The crucible of the region’s football awakening is Seattle, where attending a game at the city’s modern CenturyLink Field stadium is rapidly becoming an essential Pacific Northwest experience. Pass through Seattle’s Pioneer Square neighbourhood on a Saturday between March and October and you will be swept up by a good-natured and ebullient mood that is more characteristic of a street festival than a 90-minute spectator sport. Singing supporters spill out of old-fashioned red-bricked pubs, blue and green banners are hoisted high above crowded city squares, and a snaking procession called the “March to the Match” lines up behind The Sound Wave, a fabulous 40-piece marching band.

Even if you haven’t got a ticket for the game, it is worth visiting the pre-match parade in Occidental Park to watch the band work through its quirky music and dance routine, and bear witness to bevies of expectant Seattleites letting their hair down. Food carts set up in side streets selling tacos and hot dogs, and small stalls ply team scarves and memorabilia.  

The object of everybody’s affection is the beloved Seattle Sounders, the third incarnation of a football team founded in 1974 who joined North America’s pro league, the Major League Football (MLS), in 2009. United by their love for the game and buoyed by a penchant for jazzy re-arrangements of 1980s pop songs, the marching supporters hone in on CenturyLink Field, the deluxe 67,000-capacity stadium just south of Seattle’s downtown. 

Aided by phenomenal early success – including three US Open Cup wins in their first three seasons – the Sounders have quickly built up one of the sport’s largest fan bases. The key lies in a network of grassroots supporters spearheaded by the charismatic Emerald City Supporters and their accomplished marching band. Large, ecstatic crowds are par for the course at Sounders matches: still only in their fifth MLS season, the Sounders average home gate has reached 43,000, double that of local Major League Baseball team, the Mariners, and greater than all but five of the teams in the English Premier League, including – astonishingly – 2012 Champions League winners, Chelsea.

So what has prompted this unexpected football revolution?

Well-organised supporters groups aside, Seattle’s rapid rise has coincided with a wider renaissance within the MLS. In 2007, US football introduced its so-called “designated player” rule, loosening restrictions on foreign players and flooding the league with diverse overseas talent. David Beckham’s move to LA Galaxy was the first and biggest coup, but he was quickly followed by other stars, including ex-Arsenal ace Thierry Henry to the New York Red Bulls. These moves upped the league’s quality and international profile.

But, with average gates double those of their nearest MLS cohorts, including LA Galaxy, Seattle clearly has a few other tricks up its sleeve. The vociferous pre-match entertainment starts long before the official kick-out, with fans using social media to arrange meet ups in Pioneer Square’s pubs and parks. Off-duty players and local celebrities can sometimes be found mingling with fans.

More importantly, there is the Portland effect. Quiz any true Sounders fans about what gets their competitive juices flowing, and they will talk at length about the passions ignited by their intense rivalry with their Pacific Northwestern neighbours the Portland Timbers.

Timbers fans, who are famous for their rich litany of chants, play at the newly renovated Jeld-Wen Field  which is close enough to Portland’s downtown for supporters to stroll over after a pre-match beer in one of the city’s legendary brew pubs. With or without alcoholic beverages, going to a Timbers game can be a decidedly surreal experience. The team’s official mascot is a real chain-saw welding lumberjack named “Timber Joey” who stands behind the goal during home games guarding a scarf-draped log. Every time Portland score a goal, he saws off a slice of wood amid an eruption of sawdust and song. The hallowed slice is later presented to the goal scorer.

The Seattle-Portland face-off – by far the biggest derby match in the MLS – has ebbed and flowed since the clubs first jousted in 1975, but has taken on new meaning since the Timbers were incorporated into the MLS in 2011. Much of it stems from the region’s sporting isolation. Portland has no pro football or baseball teams to cheer for, while Seattle’s big league Seahawks and Mariners are perennial underachievers in their respective sports. The hole was further deepened in 2008 when Seattle’s pro basketball team, the Supersonics upped sticks and relocated to Oklahoma City.

Typically, the arguments go beyond football. Though Seattle and Portland are both pioneering liberal-minded cities with strong community roots, they have long traded jibes on non-sporting matters, such as the quality of their brew pubs, the hipster rating of their alternative music scenes and the potency of their single origin micro-roasted coffee. As the slightly larger, wealthier city, Seattle has historically harboured the more successful and better-supported football team. But, mention crowd numbers to self-consciously eccentric Portlanders (who usually draw around 20,000), and they will argue that, what they lack in numbers, they make up for in noise, passion and a commendable community outreach programme. Timbers players, who are noticeably more down-to-earth than their highly paid European counterparts, regularly interact with the local community, partaking in hospital visits, school training camps and establishing links with the city’s independently-minded small businesses.   

On the field, the rivalry continues to be played out in what is perhaps one of the most electric sporting occasions outside the Superbowl. When Portland and Seattle met at CenturyLink Field in October 2012, more than 66,000 supporters (the second biggest crowd in MLS history) turned up and sang themselves hoarse. The two teams meet again on 25 August 2013 when Seattle will be unveiling their latest signing, US international Clint Dempsey, a record $32 million capture from the UK’s Tottenham Hotspur. With CenturyLink’s 67,000 seats already sold out and the club allowing standing-room only tickets for the first time ever, pundits are predicting the biggest crowd in MLS history.  

Going to a Sounders game is relatively easy as long as you book tickets a few weeks in advance. Fixture lists are printed on the club’s official website. To soak up the pre-match atmosphere, arrive in Pioneer Square’s Occidental Park an hour before kick-off, when the marching band starts its rousing entertainment. Good local watering holes include the Owl ‘n’ Thistle, a football-friendly Irish pub, and Fuel, a more boisterous sports bar. The March to the Match is a short but noisy affair where first-time visitors can hold their new scarves aloft and rehearse the simple, sometimes humorous chants that are repeated throughout the game.  

Portland Timbers’ Jeld-Wen Field is situated just off the city’s bisecting north-south freeway I-405 and is served by its own MAX light rail station. Check the website for upcoming fixtures and plan well ahead. Fans warm up in pubs such as nearby Ringlers, attached to the historic Crystal Ballroom run by local micro-brewing pioneers, the McMenamin Brothers.