The unofficial opening ceremony of a Boulder summer? The Bolder Boulder.
Colorado’s signature Memorial Day tradition may technically be a 10K, but anyone who’s run it (or lined the course to cheer) knows it’s much more than a race. It’s a rolling street festival, a community-wide celebration and a heartfelt tribute to service members complete with an awe-inspiring flyover.
It’s also delightfully, unmistakably Boulder: Elite runners, weekend joggers and costume-clad participants — bananas, superheroes, flamingos, even Alan from “The Hangover” — all winding through neighborhood streets, some taking breaks to chomp on some bacon or dive down a slip n’ slide, before crossing into Folsom Field for the unforgettable finish-line celebration. Little wonder Runner’s World magazine named the Bolder Boulder “America’s All-Time Best 10K.”
The Memorial Day race is back this year, taking place on May 25. Last year, the event drew 52,054 registrants, representing 23 countries who were cheered on by more than 80,000 spectators.
While the spectacle is unforgettable, the Bolder Boulder backstory is just as compelling and full of surprising history tidbits, unique traditions and Boulder moments that have defined the race for nearly five decades.
Here are 10 things you may not know about one of Colorado’s most iconic events.
1. The Bolder Boulder Started Small
Today, the Bolder Boulder draws tens of thousands of participants. But back in 1979, the inaugural race started with a smaller footprint, with just 2,700 registrants, according to the event’s history.
Runners crossed at North Boulder Park, where medals were handed out to age-group champions and finishers received certificates commemorating the accomplishment. It was humble by today’s standards, and just the beginning.
2. Folsom Field Wasn’t Always the Finish Line
One of the most exciting moments in the race is entering the University of Colorado’s home turf and finishing on the field to roaring cheers echoing throughout Folsom Field.
But that iconic finish wasn’t always part of the race. The tradition began in 1981. After the 1980 race, which ended at Boulder High School, race co-founder Steve Bosley (who later became a CU regent) was approached by then-CU athletic director Eddie Crowder with the idea to bring the race’s grand finale inside Folsom Field.
The race’s official starters have included several CU luminaries over the years, including CU Superfan “Miss Peggy” and CU Hall of Fame inductees Emma Coburn and Jenny Simpson Barringer.
3. An Olympic Star Helped Shape the Race
The Bolder Boulder has serious running credentials.
Race co-founder Frank Shorter, who won two Olympic marathon medals — a gold at the 1972 Summer Olympics and a silver four years later at the 1976 Summer Olympics — helped establish the event. He also won the Bolder Boulder in 1981.
The next time you’re downtown, stop by the Bolder Boulder Spirit of Frank Shorter mural at the corner of Spruce Street and Broadway. Originally painted in 1997 to celebrate Shorter, who is often credited with helping spark America’s running boom in the 1970s, the mural was refreshed and expanded in 2025 by its original creator, artist Jim Nelson.
4. The Wave Start Was a Game Changer
If you’ve ever run the Bolder Boulder, you know participants start in staggered groups, or “waves,” based on pace.
That innovation debuted in 1983, helping everyone from competitive runners to casual joggers have a smoother race experience. It was a logistical breakthrough that many major races now emulate.
The Bolder Boulder is also recognized as a pioneer for offering equal prize money for male and female winners, according to Run, a media platform from Outside.
5. It Became the Biggest Timed 10K on Earth
By 2004, the Bolder Boulder earned bragging rights as the largest timed 10K in the world, with 47,454 hitting the pavement, according to the race’s historical timeline.
By the time the Bolder Boulder celebrated its 40th anniversary in 2018, roughly 1.3 million people had finished the race over the event’s history.
6. The Race Has a Global Reach
The Bolder Boulder spirit stretches far beyond Boulder County.
In 2006, organizers launched a “Base Race” in Baghdad, where 601 deployed service members competed in the satellite event. The program soon expanded to more U.S. military installations around the world, including aboard a U.S. Navy aircraft carrier, where participants complete the race on treadmills. This gives deployed troops a chance to join from afar.
According to Bolder Boulder organizers, more than 25,000 service men and women have taken part in the Memorial Day tradition while deployed, receiving custom race gear, a shared race-day experience and a complimentary entry to run the Bolder Boulder in Colorado upon returning home.
7. There’s a Shirt You Can Only Earn by Outrunning Time
One of the coolest race-day honors? Becoming an Ageless Wonder.
If your 10K finish time is faster than your age — say, a 65-year-old finishes in 64:59 — you earn a coveted Ageless Wonder shirt.
8. Speaking of Age … The Oldest Finisher Was 100 Years Old
Among the most beloved runners was George Pierce, who completed the race eight times, beginning at age 89. He finished his last race in 2024 at age 100 and passed away in 2025 at age 102.
At 100 years old, he finished his final Bolder Boulder wearing jeans, cowboy boots and a cowboy hat—proving endurance doesn’t always come in moisture-wicking fabric. He became a race-day legend, embodying Colorado grit and spirit.
9. The Number of Women Racers Outnumber Men
The Bolder Boulder reached a milestone in 1995 when female participants outnumbered men for the first time. That momentum has continued ever since, with females frequently accounting for about 60 percent of all runners.
10. The Bolder Boulder is Good for the Economy
The Bolder Boulder is a major economic engine for the region. According to Visit Boulder, the race generated a $23 million economic impact in 2024, up $4.2 million from the previous year, driven by visitors who fill local hotels, dine at local restaurants, and shop in Boulder businesses during race weekend.
