Tens of thousands of runners are gathering in Denver this weekend for the 20th [1] running of the Colfax Marathon.

The event serves as a major community engagement and fitness initiative, drawing significant crowds to one of the city's most prominent thoroughfares. Because of the scale of the races, city officials have coordinated extensive road closures and transit adjustments to manage the flow of people and vehicles.

The weekend festivities feature eight [1] separate races. Marathon Director Jeff Hensley said the event expected a record-breaking field with more than 20,000 [3] participants across those races.

Despite the high volume of athletes, the event has faced logistical hurdles due to city infrastructure projects. Denise Lavoie said the marathon would go ahead as planned despite the ongoing construction on Colfax Avenue [2].

The impact of the races extends beyond the runners to the general commuting public. RTD spokesperson Karen Mitchell said riders should allow extra travel time this Sunday as buses and light-rail trains will be detoured around the marathon route [4].

Organizers designed the 20th anniversary event to promote fitness while navigating the complexities of an active urban environment. The coordination between the marathon committee and city transit authorities aims to minimize the disruption caused by the massive influx of participants and spectators along the route.

“The 20th running of the Colfax Marathon featuring eight separate races.”

The Colfax Marathon's ability to maintain its scale despite ongoing urban construction reflects the event's deep integration into Denver's civic identity. By coordinating with RTD and city officials, the organizers are balancing a large-scale public health and community event with the practical needs of city infrastructure and transit.