High school football players on 14 mostly Bay Area teams convene one Saturday in Pittsburg. They engage in the modern summer ritual of 7-on-7, a scaled-down version of the game featuring quarterbacks flinging passes and receivers trying to outmaneuver defenders.

About the series
For years, mounting evidence has linked football violence with brain trauma and life-threatening conditions. Now that we know the sport can produce deadly results, where do we go from here? The Chronicle offers this special report on The Future of Football.

The players wear shorts and practice jerseys. Some don soft headgear, but what’s missing is notable: no linemen, no helmets or shoulder pads, no tackling.

Less than three weeks later, in Houston, several former pro players — including onetime Cal running backs Jahvid Best and Justin Forsett — compete in the American Flag Football League final. NFL Network televises the game. Again: no linemen, no helmets or shoulder pads, no tackling.

Is this what football will look like in the future?

De La Salle’s Grant Daley is pursued by Antioch’s Ke’Sean Patton during a 7-on-7 tournament featuring 14 high school teams in Pittsburg this past summer.

(Carlos Avila Gonzalez / The Chronicle | San Francisco Chronicle)

That might seem extreme, but envisioning how America’s most popular spectator sport will be played in 20 or 30 years carries complications. As participation at younger levels dips amid concerns about concussions and the degenerative brain disease chronic traumatic encephalopathy, and as the pro and college games adopt rules changes intended to make an inherently violent sport safer, the future becomes murky.

Participation in high school football in the U.S., which peaked in 2008, fell 6.9 percent by 2017, according to the National Federation of State High School Associations (NFHS), to 1,035,942. (Football still counted as the nation’s most popular boys sport by a wide margin.) The drop in California was even more severe: from a peak of 107,916 in 2006 to 94,286 in 2017, per the California Interscholastic Federation. That’s a decrease of 12.6 percent.

Moreover, football players sustain more concussions than other high school athletes, according to a 2017 study in the Journal of Athletic Training. That report, covering the 2011-12 through 2013-14 school years, found football players are 16 times more likely to suffer a concussion than baseball players, and four times more likely than male basketball players.