The Bolder Boulder will start Monday morning with nearly 53,000 entrants, putting the 46th annual race on track for a top-five finish in total registrations in its history. Registrations closed Friday at midnight, and the field was already about 700 entrants larger than it was at the same point in 2025.

That kind of volume matters because the race typically picks up at least 1,000 more registrations on race morning, meaning the final count could still climb before the first runners step off. This year’s turnout would also put the citizen’s race among its biggest fields in decades, even after a final pre-race weekend that for the first time since 1979 did not remain open for last-minute signups.

Cliff Bosley, who helps track the event’s numbers, said the surge fits a broader pattern in running. Broadly, he said, the sport keeps getting more popular. He pointed to the pandemic years, when many people took up running because it was something they could do while staying fit and keeping busy when the world was closed down. People were gravitating outdoors, he said, toward hiking, walking and running.

The numbers back that up. The race drew 33,991 entrants in 2022, its lowest mark since 1991, then climbed to 40,044 in 2023, 43,971 in 2024 and 52,054 last year. The Bolder Boulder peaked in 2011 with 54,554 entrants, and between 2007 and 2019 it topped 50,000 entrants in 10 of 13 races. A separate high-water stretch included nine races in 10 years with at least 50,000 entrants, interrupted only by 2013, when the race drew 48,300 entrants after the Boston Marathon bombing helped contribute to the total.

The event was forced into a two-year hiatus in 2020 and 2021 during the pandemic, but its rebound has been steady since returning. Last week, the Denver Colfax Marathon sold out its half-marathon, another sign that road races in the region are drawing strong interest, Bosley said. He said that could be another indicator that interest in road racing is increasing.

Sunday’s cutoff also reflects something less celebratory: the race had to close registrations before the final weekend to stay within operational capacity. Still, Monday’s field will be the largest in more than a decade, and the race will again finish with the International Team Challenge and the annual Memorial Day tribute.

Not every major name will be on the line. Three-time defending champion Conner Mantz is still recovering from an injury, and two-time defending women’s champion Grace Loibach Nawowuna of Kenya will not compete. Even so, the scale of the field suggests the Bolder Boulder has not just recovered from its shutdown years. It has moved back into the tier of races that can fill up fast and keep growing.