More than 28,000 runners [1] participated in the 20th anniversary of the Denver Colfax Marathon on May 14, 2026 [2].

The milestone event maintains the city's status as a hub for distance running and serves as a qualifying race for the Boston Marathon [3].

Organized by the Colfax Marathon team under CEO Andrea Dowdy, the event featured a variety of distances to accommodate different skill levels. Participants competed in a full marathon, a half-marathon, a 10-mile race, a 5K, and a marathon relay [4].

The races took place primarily along Colfax Avenue and surrounding streets in downtown Denver [5]. To accommodate the high volume of participants, the city implemented rolling road closures throughout the weekend of May 14-15 [2, 6]. These closures impacted several major thoroughfares to ensure the safety of the 28,000-plus [1] athletes.

The 20th edition [2] of the race marks two decades of the event's presence in the Colorado capital. The marathon has grown into a significant regional draw, combining community celebration with high-level athletic competition.

Local authorities coordinated the traffic diversions to manage the influx of runners and spectators in the downtown corridor [5]. The event concluded its anniversary celebrations on Friday, following the primary races held earlier in the week.

“More than 28,000 runners participated in the 20th anniversary of the Denver Colfax Marathon.”

The sustained growth of the Colfax Marathon to over 28,000 participants demonstrates the increasing economic and cultural impact of urban endurance events. By maintaining its status as a Boston Marathon qualifier, Denver secures its position in the global competitive running circuit, attracting international athletes and boosting local tourism.