It was at a bar in Nairobi, sometime in 2009, that I really started to understand. It was dark. Pints of Tusker beer were served at room temperature. And when soccer matches were on, there was no idle talk. 

The English Premier League was a part of life in Kenya. Often, entire communities would follow the same club. It didn’t matter that they played a continent away. Any scrap of news was relayed, examined and considered. Sports pages were passed from person to person for days beyond the publication date.

At first, I didn’t get it, then realized that didn’t matter. It wasn’t about me, and it wasn’t anyone’s responsibility to explain it to me. This was happening whether I was involved or not.

I’ve come to understand it as a reflection of how soccer has expanded in the U.S.: People are having a blast, and they don’t care who’s with them.

That’s how it was in Glendale on Thursday night, when about 30,000 fans, many wearing the colors of the Mexican national team, showed up to watch Gold Cup tournament play. And that’s how it’s been in Scottsdale, where eight times since March about 6,500 people have packed into the pop-up stadium where United Soccer League club Phoenix Rising FC plays.

The numbers that point to soccer’s growth are undeniable. Half of the MLS’s 22 teams are averaging more than 20,000 in attendance. There’s a new team coming to Los Angeles. David Beckham is pushing for a side in Miami (thanks to a deal he cut as a player with the LA Galaxy). And ownership groups in a dozen cities, including Phoenix, are bidding to become one of four MLS expansion clubs.

MLS average attendance is third among major pro sports, behind the NFL and Major League Baseball. And Atlanta United, which draws 46,000, has the highest average attendance of any U.S. sports team outside of the NFL.

MLS executive Dan Courtemanche said millennials are leading the way, providing figures that show his league has the youngest fan base in American pro sports.

This sounds about right to me. I’m old for a millennial, but in the demographic. We’re famous for doing things our own way. We watch TV on our phones (even sports.) We talk with our thumbs (often using little pictures instead of words.) And our rap stars sing love songs (which even I don’t get, but that’s probably my Gen X showing.)

Makes sense that we would be the group to finally embrace soccer after years of predictions that the sport would take off in the U.S.

Rising Chief Operating Officer Bobby Dulle said his ownership group recognizes that there is “a need and a want” in the market and that Phoenix “deserves soccer at the highest level.”

“We’re putting our best foot forward,” he said. “We don’t want to stop until we get where we want to go — which is to the MLS.”

It’s not without risk. In Kansas City, for example, the Wizards played to empty seats in Arrowhead Stadium.

The club took off in 2010 after rebranding as Sporting KC and focusing on a fan experience that includes “the Cauldron,” a rocking section where 20-somethings wear scarfs while they drink and chant and stand for entire matches. In 2011, Sporting KC built a soccer-specific stadium, and they’ve been selling the place out since 2012. Sure, there are a lot of Chiefs and Royals fans who still don’t get it, but that hasn’t stopped the party.

There is no such thing as a fan who isn’t invested – no passion, no ticket sales.

Look no further than University of Phoenix Stadium for proof. As Jamaica played Canada in the Gold Cup, there were huge sections of empty seats. Most of the scattering of fans who came out were visibly supporting Mexico.

But by the time Mexico took on Honduras, the stands were as green as the pitch, with Mexico fans showing their colors, wearing sombreros and waving flags.

Phoenix Rising seems to be conscious of reaching out to fans and has fostered a partnership with the Arizona Youth Soccer Association.

Claire Miller, of the Salt River Pima-Maricopa Indian Community and president of Solanna Group LLC, which owns the land where the Rising FC Soccer Complex is situated, said she is optimistic in part because the club has been “very, very open to working with the tribal community.”

“We all have the same goal,” she said. “We expect to go to the MLS, very much.”

A decision will come down on the first two teams of the four-team expansion this year.

Whether you catch on will be up to you.

When I was in Kenya, I learned when to shout, hold my breath and pound the table watching clubs like Liverpool, Manchester United and Arsenal.

Since then, I haven’t paid much attention outside of World Cups. That hasn’t stopped anybody else, and the numbers show it.

Reach Moore at [email protected] or 602-444-2236. Follow him at twitter.com/WritingMoore.