Event details subject to change. Please confirm all information via event website.
Chilly Cheeks Winter Duathlon
Cherry Creek State Park 4201 S Parker Rd, Aurora, CO, United StatesThe Chilly Cheeks Duathlon Series is now a stand-alone event held in late February. The 63rd Chilly Cheeks Duathlon will be held in the traditional format of Run-Bike-Run. Both runs will be 2.5 miles in length and the bike course will be an 11 mile paved road route. As always, we will provide a marked […]
That DAM Run Half Marathon
Get ready for the Best Dam Run you'll ever do! From your first step to your finish-line celebration, this race is packed with epic views, big accomplishments, and just the right amount of dam fun. Choose from a Half Marathon, 10K, or 5K as you race along Cherry Creek Dam with panoramic views of Denver and the […]
Runnin’ of the Green Lucky 7K
Feeling the luck o' the Irish? Lace-up and chase the rainbow in Denver’s favorite Irish-themed run! Join us at Washington Park for some shenanigans! Runnin' of the Green (ROTG) is a family-friendly 7K and 2 Mile race/walk celebrating Irish traditions, Saint Patrick’s Day, and Spring! The event promises to be a day filled with Irish fun, live music, awards, […]
Far Out 3/4 Marathon
Chatfield State Park 11500 N. Roxborough Park Rd, Littleton, CO, United StatesWe host one race per month from November to March. All races are at Chatfield State Park and start at 9:00 am on Saturday mornings. Check-in starts at 8:15 am.
Three Creeks Half Marathon
Racing Underground brings you an amazing half marathon this spring! The Three Creeks Half Marathon features a half marathon course that is flat, fast and scenic! Travel on foot through some of the most beautiful parts of Cherry Creek State Park, with a total combined elevation gain of only 291 feet spread out over 13.1 […]
Donut Dash
The Donut Dash 5K is Denver’s race that ends with doughnuts. Runners and walkers can take advantage of a flat and fast course, and then enjoy fresh doughnuts at the finish. Our mission is to bring people together to have a fun, fit morning.
Mountain Ridge Trail Race
Mountain Ridge takes place near Highlands Ranch primarily on the Douglas County East-West Regional Trail. This gently rolling course will keep the Heart Rate pumping while offering some of the best views in the front range. The Mountain Ridge Trail Race will once again start and finish from Mountain Ridge Middle School, and offer 100% […]
Platte River Half Marathon
Denver's oldest half marathon runs along the Platte River Trail, covering parts of Littleton and Denver.
Rattler Trail Race
Rattler was created to feature one of Colorado Springs' best city parks, Palmer Park. Runners will enjoy views of the city and Pikes Peak from the sandstone bluffs, while running all of the best trails the park has to offer! Even though the course does not have much vertical gain, it will test runners with […]
Royal Gorge Groove Trail Runs
Prepare for some fun in Cañon City! Enjoy scenic views along the rim of the Royal Gorge, 900 feet above the Arkansas River. All races will start/finish at the Royal Gorge Ranch & Resort. Distances include a 50K, 30K, 20K, 13K, 5K and Kids Run. Make a weekend out of it with river rafting and […]
Greenland Trail Race
The Greenland Trail Race offers four outstanding distances in southern Douglas County. Run the 4 Miler, the 8 Miler, the 25K, or tackle the 50K ultramarathon, Colorado’s fastest 50K! With Pikes Peak as your backdrop, you’ll cruise over a soft dirt trail on your way to a new personal best. With chip timing, an innovative technical running shirt in men’s and women’s sizing, food and beer at the finish, this race will make you want to come back for more!
Colorado Marathon
Marathon, Half Marathon, 10k, 5k and 3-Person Marathon Relay. Marathon, Marathon Relay and Half Marathon runners get to run down the scenic, downhill Poudre Canyon to the finish in Old Town, Fort Collins, where we have live music and a big post-race party featuring beer from Odell Brewing Company. For 2027 Boston Marathon qualifiers, races […]
Wine Run 5K
Like Running or Walking? Love Wine? This race is for you! Join us on Saturday, May 8, 2027 at 9:30am and 11:00am (you will pick your start time during registration) for an exciting annual event that features the amazing scenery and landscape of Colterris Winery! With over 75 acres of vineyards, Colterris is Colorado’s largest […]
Ram Party Trail Runs
With plenty of race options for everybody centered around the beautiful Rampart Reservoir in Woodland Park, Colorado, you're sure to have a good time while you take in the epic views of Pikes Peak and the front range. 55 Mile | 60K | 50K | 24K | 15K
North Fork Trail Race
The North Fork 50 Mile/50K is 100% trails, mainly single track and some double track, starting and finishing along lovely Buffalo Creek, in the mountains about 50 miles southwest of Denver. This is a pure ultra, a very special and unique race, deliberately kept small so each runner gets personal attention. There are no non-ultra […]
Barr Lake Trail Race
The Barr Lake Trail Race returns to Brighton, CO, offering beautiful lake views and a prime opportunity for new PRs. Now in its sixth year, this event features our flattest and fastest course, with less than 100 feet of elevation gain per loop. Starting and finishing at the Nature Center, runners will enjoy a scenic […]
Colorado Triathlon
The Colorado Triathlon is where Colorado comes to race! The Colorado Triathlon - sprint & olympic distances, duathlon & aquabike options . To make this the "can't miss" event of the season, we'll also have athlete hoodie sweat shirts, and the best swag bag of the season. For us this race is about one person, […]
Lory Off-Road Triathlon
XTERRA Lory Triathlon is the perfect kick-off to the year for the seasoned off-road triathlete, or a great opportunity for the road triathlete wanting to try out a mountain bike triathlon for the first time. The XTERRA Lory Triathlon features a 1/2 mile swim in the clear waters of Horsetooth Reservoir (Eltuk Bay), it's one […]
Ring the Springs Trail Races
Get ready for an unforgettable adventure at Ring the Springs trail running races in the stunning Colorado Springs, Colorado! This thrilling event showcases the area's incredible natural beauty, with a course that weaves through majestic mountains, scenic city parks, and iconic landmarks. The route is designed to challenge and inspire, featuring exhilarating climbs and rewarding […]
Boulder Peak Triathlon
The Boulder Peak Triathlon, Duathlon & Aquabike on July 10th is one of the countries longest and most well-known triathlons. For the veteran or first time racer, this is THE can’t miss event of the summer triathlon season, and the crown jewel of the Colorado Triathlon Series. Racers are tackling the infamous “Olde Stage” Hill, […]
Silverton Alpine Marathon
Experience the best of the San Juan Mountains with an 8 miler, a marathon, or a 50 kilometer run along the Alpine Loop past the historic mining ghost towns of Howardsville, Eureka, Animas Forks & Gladstone. High point is 12,930 ft atop California Pass. Low point is Silverton at 9,318ft. Total vertical gain is 3,800 […]
Kendall Mountain Run
Meet the mountain this summer in Silverton, Colorado! The Kendall Mountain Run starts in downtown Silverton and traverses jeep roads to within a final 300 vertical foot scramble to the summit of Kendall Mountain overlooking town and the majestic San Juan Mountains. Ascend from 9,318 feet to 13,066 feet to tag the summit! Experience the […]
Steamboat Lake Triathlon
After last summer this event instantly became a personal favorite for our staff, volunteers, and athletes - come find out why! We couldn't be more excited about this course, this lake, and the overall experience. The swim starts out in the surprisingly warm waters of Steamboat Lake (74 degrees average race temp), then athletes transition […]
Backcountry Marathon
Utilizing the beautiful trails that surround Aspen, and now offering three distances - 50K, marathon and heavy half-marathon, all of which run almost exclusively on dirt trails. For the first time in 2025, Aravaipa is introducing an ultra distance that will follow the marathon course and include an out and back to the McNamara Hut […]
Stagecoach Gravel Triathlon
We didn't get the chance to launch this race in 2020, but that didn't diminish our passion for this brand new style of triathlon! To say this race is “unique” would be an understatement! Limited to just 250 athletes, we're excited to announce the first ever gravel triathlon to the Colorado triathlon landscape! This event […]
Westminster Trail Race
Wayne Carle Middle School 10020 100th Ave, Westminster, CO, United StatesAfter a special night edition last year, Westminster returns to its traditional daytime format in 2026 — bringing runners back to a classic morning on the trails at Standley Lake. Now in its 12th year, Westminster Trail Race continues to be one of the Front Range’s most approachable and scenic trail events. The courses wind […]
PPRR Nielson Challenge
North Monument Valley Park 1794 Culebra Ave., Colorado Springs, CO, United StatesRace Format The first time you run this event, you'll establish a base time for yourself. This base time is used to generate a handicap time. The handicap time is calculated using an algorithm developed by Bob Royse, and it's geared to favor a beginning runner and the slower runners. Click here for an explanation of the […]
Outdoor Divas Triathlon
The Outdoor Divas Sprint Triathlon on August 21st, annually awarded best women's event in Colorado by Competitor Magazine, is the all women's triathlon you've been waiting for! We intentionally keep the race cap low at 600 women to create a fun, festive, yet intimate racing environment. Great goodie bags, one of our biggest expos of […]
Chase the Moon Trail Race
Chase the Moon is a 12-hour team relay and solo ultramarathon, run overnight under the light of the full moon in the Highlands Ranch Backcountry trail system (we promise some of the best views of the metro and front range). Run as a solo ultrarunner, or get your fellow moon-chasing friends for a 3-person or […]
Rock Hawk Trail Race
Held on the gorgeous, thrilling and rolling trails of Castle Rock’s Miller Park & Ridgeline Trail systems. While not overly technical, these trails will challenge and excite, as you soak up the amazing views. This is an excellent race for both first-time and veteran trail runners, and provides a nice test for those who are […]
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