You could see it in the seaside park in Redondo Beach, normally a haven for moms and scuba divers, but now packed with more than 1,000 seething, war-painted fans.
Or outside the gates of Disneyland, where the throng rose and put on extra-big voices to sing the national anthem.
Or at countless desks, counters and loading docks, where laptops and smart phones glowed with the signal from Arena Fonte Nova in Salvador, Brazil.
America was looking for a rare breakthrough Tuesday into the quarterfinals of soccer's World Cup, and Southern California leaned in, held its breath and stopped to take notice. From mass viewing parties to solo living-room vigils, the showdown with Belgium captivated much of the Southland for 90 minutes of regulation and 30 minutes of extra time.
Even as the Americans' desperation comeback fell short, 2-1, fans celebrated both their love of soccer and of finding a common cause in a sport many of them had only realized they could like in the last two weeks.
For Josh Sanchez of Riverside, the best moment came at the beginning, when the crowd at Downtown Disney in Anaheim joined the players on the jumbo screen, hands over their hearts, singing the "Star Spangled Banner."
"You could feel something happening," said Sanchez, 18, his hair sprayed red and white, his shoulders draped in an American flag. "You're not the only one feeling it. This entire group of people standing next to you is also feeling it."
The same might have been said of the American team's entire two-week run in the world's most popular sporting event. Fans who had spent their lifetime worrying about free throws and first downs suddenly tuned in. They tried on a new language of touch lines and challenges and players who were "good in the air."
Team USA offered personalities and intrigues and fans rallied around that too. Would striker Jozy Altidore recover from a dubious hamstring (he wouldn't), would indomitable goalie Tim Howard rise to the occasion (he would) and could American grit find expression on something called a pitch (it did)?
"It's night and day from what it was four years ago," said Todd Hummer, 48, watching with his daughter, Merae, her club soccer teammates and about 20 others at a packed Claremont restaurant. "Nobody then would have known what was going on. Now I have friends saying 'I'm taking off work to see the game.' It's amazing."
The increased interest has been borne out in high ratings for World Cup games. A first-round match between the U.S. and Portugal drew a record for U.S. soccer viewership — more than 25 million people tuning in across multiple TV stations and mobile apps. Some games in the 32-team tournament have drawn more viewers than even the NBA finals and baseball's World Series, something once unthinkable.
There they were Tuesday, futbol fans jamming the floor of Soldier Field in Chicago, embracing their emotive, technical sport, where Dick Butkus once defined the brutality and raw power of American football. The same at AT&T Stadium in Arlington, Texas, home of another "America's team" — the Dallas Cowboys. And the same at a mid-street viewing space in Long Beach, where the city held its first-ever public viewing party.
Wearing a blue sweater with USA in white lettering, Marynieves Aguirre of Diamond Bar had arrived by 8 a.m. and soon had a spot on the curb. Small American flags were tucked in her black purse as she watched a prior game between Argentina and Switzerland.
"I'm very happy and I believe the U.S. will win, 2-0," said the 46-year-old Aguirre. She chuckled and added, "I'm an optimistic person."
The much-anticipated match would not start well for the U.S. Less than a minute in, Belgian speed merchant Divock Origi exploded past the defense, thwarted only by the first of Tim Howard's brilliant saves. For much of the afternoon it continued that way: The artful Europeans breaking free, only to be shut down by the U.S. keeper.
Only in extra time, down 2-0, did America finally break through with a goal by 19-year-old Julian Green. Suddenly there was a chance for late redemption. It didn't come, but it left many fans with the feeling that the Americans might have a future.
Steve Barchan used his iPhone to watch the game on the sly at his desk at an Arcadia flooring company. The 56-year-old compared the U.S. team to the Los Angeles Kings, recently crowned champions of pro hockey.
"You have to admire a team that is running on guts and fumes like that," Barchan said. "Maybe they didn't completely belong, but they got a lot further than people thought they would. I am proud of them for that."
Shirley Dolan, 73, suffers from arthritis and doesn't stray from home much. But the games had taken over her TV in recent days and sparked something.
"It gets you motivated," she said. So she made her way to the Redondo Beach park to join an event that L.A.'s professional soccer team, the Galaxy, helped organize. Her son Robert, 49, pronounced himself "excited, exhilarated and proud" at how well America had done.
At the Bunker Hill Bar & Grill in downtown Los Angeles, lawyer Michael Galas praised the "inspired futbol" at the end. He had been in Brazil for the U.S.' first three games and now joined others in business attire and red, white and blue accessories. "It's a lot to build on. This wasn't supposed to be our year," he said.
Some American fans were already regrouping and picking backup teams — would they now cheer for proven teams and stars like Brazil's Neymar and Argentina's Lionel Messi, or go with underdog Costa Rica, or budding phenom James Rodriguez of Colombia? So many decisions to make, as the diminutive gold cup remained within reach of eight teams.
Others were already looking forward to Russia 2018 and what they hoped would be the next chance for team USA.
Outside Disneyland, Silvia Taltique of New Braunfels, Texas, wished that she didn't have to wait years to recapture Tuesday's feeling — the crowd chanting "USA" and "I believe we can win," even as overtime slipped away.
"We need to find the true meaning of why we're here in the first place," Taltique said. "This camaraderie shouldn't just happen every four years. Everybody should always try to seek common ground."