The Colfax Marathon had about 21,000 runners last year and sold out both the full and half marathon categories.
This year, organizers are responding to the event's growing popularity by changing the race's route for its 18th year to accommodate more runners.
"The Denver Colfax Marathon is now the largest marathon weekend in the 8-state Rocky Mountain region," said Andrea Dowdy, CEO of the Denver Colfax Marathon, in a statement this week. "We have one of the most scenic race routes in the country. From the mountains to water views, the iconic local landmarks to the unbeatable entertainment along each race, the magic of the marathon weekend is about to get even better."
The adjusted course will separate marathoners and half-marathoners for a portion of the course, allowing for greater capacity for both races in the future.
Half-marathon runners will will take a different course through the Denver Zoo through the Down Under and Flamingo Habitats. Elsewhere in the course, marathon runners will take up the entirety of the Cherry Creek Bike Path, while half-marathoners will run down Speer Boulevard. The two courses will also separate into two lanes on Lawrence and 17th Ave.
The 2024 marathon will feature eight races, with a 5k on May 18 and the marathon, half-marathon, 10-mile race and marathon relays on May 19. It's the only marathon in Denver and runs through Empower Field, a fire station, the Denver Zoo and a number of other Denver landmarks.
Interested racers can register online while spots are available.