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★ Marquee Returning Discontinued Unverified~ Date not confirmedDiscontinued and unverified events are listed, but not counted.

• January
• JAN2026

  Sourdough Snowshoe Race

  UnverifiedReported by a source but not independently confirmed. Check before entering.

  Roosevelt National Forest backcountry; ~10,000 ft. Donation-based winter/snowshoe event. Could not be independently confirmed as a currently active event — verify directly with Trail Trash Adventures.

  NederlandDenver Metro & Foothills
  30K18K
• February
• FEB 6–72027

  Stories Ultra

  No podium/age-group awards, per HPRS format.

  Also offers Half, 10K

  Colorado SpringsColorado Springs / Pikes Peak
  Timed30-hr15-hr6-hr
• April
• APR2027

  Royal Gorge Groove

  Royal Gorge area.

  Also offers 30K, 20K, 13K, 5K

  Canon CitySouthern Colorado
  50K
• APR 112027

  NoCo Urban Ultra & Relay

  Urban Greeley course. Solo or relay options for both distances.

  GreeleyNorthern Front Range
  100 mi50 mi
• APR 172027

  Rattler Trail Race

  Palmer Park.

  Also offers 25K, 10K

  Colorado SpringsColorado Springs / Pikes Peak
  50K
• APR 252026

  Cheyenne Mountain Trail Races

  Cheyenne Mountain State Park. Distances confirmed: 50K / 25K / 10K.

  Also offers 25K, 10K

  Colorado SpringsColorado Springs / Pikes Peak
  50K
• APR 252026

  Falcon 50

  Front Range foothills. Featured on the UltraSignup Colorado list.

  Colorado SpringsColorado Springs / Pikes Peak
  50 mi50K
• May
• MAY2027

  Collegiate Peaks Trail Run

  Long-running local race in the Collegiate Peaks area near Buena Vista. Specific 2027 date unconfirmed.

  Also offers 25 mi

  Buena VistaCentral Mountains / Sawatch
  50 mi
• MAY2027

  North Fork Trail Race

  100% soft-surface singletrack; 1996 burn-scar terrain SW of Denver (Buffalo Creek area). Proceeds support the North Fork Volunteer Fire Dept.

  PineDenver Metro & Foothills
  50 mi50K
• MAY 22026

  Greenland Trail Races

  Greenland Open Space (near Larkspur). 2026 RRCA National 50K Championship; billed as 'Colorado's fastest 50K'.

  Also offers 25K, 8 mi, 4 mi

  LarkspurColorado Springs / Pikes Peak
  50K
• MAY 22026

  Take 5 in the Garden

  Garden of the Gods area. Timed ultra-format event; specific duration not listed in source — confirm with organizer.

  Also offers Road + trail short options

  Colorado SpringsColorado Springs / Pikes Peak
  TimedTimed (duration TBD — verify with organizer)
• MAY 92026

  ★Quad Rock 50/25

  Lory State Park & Horsetooth Mountain Open Space. Anchor race of the 'Gnar Slam'.

  Also offers 25 mi

  Fort Collins / BellvueNorthern Front Range
  50 mi
• MAY 92026

  Valkyrie Trail Race

  Cheyenne Mountain State Park. Women-centered trail event.

  Also offers Marathon, 30K, Half, 8 mi, 4 mi

  Colorado SpringsColorado Springs / Pikes Peak
  50K
• MAY 162026

  Ram Party Trail Runs

  Rampart Reservoir / Buffalo Lodge Bicycle Resort; high point 9,500 ft. Weekend festival format.

  Also offers 60K, 24K, 15K

  Colorado SpringsColorado Springs / Pikes Peak
  55 mi50K
• MAY 222027

  Samson's Revenge Trail Race

  Estes Park / RMNP-area foothills.

  Also offers 27K, 10K

  Estes ParkEstes Park / RMNP
  55K
• MAY 232026

  GMR Backyard Ultra

  GoldenDenver Metro & Foothills
  BackyardBackyard · 4.20 mi loop
• June
• JUN 5–62027

  Weld Your Mettle Running Festival

  Plains terrain (not mountain). Virtual option available.

  Also offers 7K, Relay options

  EatonNorthern Front Range
  Timed36-hr24-hr12-hr9-hr+2
• JUN 6–72026

  ★The Great Divide Ultra

  Mueller State Park; rolling single/doubletrack; 9,000+ ft elevation. First 100-miler on the CO calendar each year; non-technical; features a night 'Dark Divide' run. Three start-time variants per distance.

  Also offers 25K

  DivideColorado Springs / Pikes Peak
  100 mi100K50K
• JUN 132026

  Barr Lake Trail Race

  Flat and fast course around Barr Lake State Park.

  Also offers 30K, Half, 15K, 5K

  BrightonDenver Metro & Foothills
  50K
• JUN 132026

  Summits Trail Runs

  Granby Ranch. Confirmed distances: 50K, Marathon, Half Marathon, 6 mi, plus a 14-hr timed 'Elevation Challenge' option.

  Also offers Marathon, Half Marathon, 6 mi

  GranbyMountains / Western Slope
  Timed50K14-hr timed
• JUN 202026

  Ring the Springs

  Ring the Peak trail system.

  Also offers 35K

  Colorado SpringsColorado Springs / Pikes Peak
  100K50K
• JUN 202026

  ★San Juan Solstice 50

  San Juan Mountains; ~12,000 ft climb along the Continental Divide. Lottery entry (300 runners); Western States qualifier; benefits Lake City EMS.

  Lake CitySan Juans
  50 mi
• JUN 272026

  Chase the Moon 12 Hour Endurance Run

  Overnight 7 PM–7 AM run under the full moon. Offers a standard 50K option alongside the timed formats.

  Also offers 6-hr, 3-hr, Relays

  Highlands RanchDenver Metro & Foothills
  Timed12-hr50K
• JUN 272026

  Estes Park's Backyard Ultra

  Lake Estes paved loop.

  Estes ParkEstes Park / RMNP
  BackyardBackyard · 4.25 mi loop
• July
• JUL2026

  Grand Mesa Ultras

  World's largest flat-topped mountain; alpine lakes; 10,000+ ft. Cash prizes for top 3 M/F; on-mountain camping.

  Also offers 30K

  Grand MesaMountains / Western Slope
  50 mi55K
• JUL2026

  ★Hardrock Hundred Mile Endurance Run

  San Juan Mountains loop; ~33,000 ft climb; avg elevation 11,186 ft; summits Handies Peak (14,048 ft — highest point in any race in this dataset). One of the hardest ultras in the world to enter: lottery + trail-work requirement. Part of the Grand Slam of Ultrarunning.

  SilvertonSan Juans
  102.5 mi
• JUL2026

  ★High Lonesome 100

  Sawatch Range; Collegiate Peaks region; five alpine passes; 13,150 ft high point. Two-pool lottery; trail-work requirement; Western States qualifier; competitive/elite field.

  Mount Princeton / Buena Vista areaCentral Mountains / Sawatch
  100 mi
• JUL2027

  Leadville Silver Rush 50

  ReturningCancelled for a season, expected back — listed as a typical year.

  High-altitude mining-road course above 10,000 ft. 2026 run cancelled due to Willow Fire (per The Colorado Sun, July 9, 2026). Expected to return; this entry represents a typical year.

  Also offers Marathon

  LeadvilleCentral Mountains / Sawatch
  50 mi
• JUL2027

  ★Ouray 100 Mile Endurance Run

  ReturningCancelled for a season, expected back — listed as a typical year.

  San Juan Mountains; ~41,862 ft gain; historic mining routes. 2026 edition cancelled ~2 weeks before race day due to Gold Mountain wildfire. Expected to return; this entry represents a typical year.

  OuraySan Juans
  100 mi
• JUL 10–112026

  Silverheels Trail Runs

  Avg elevation over 10,000 ft. May correspond to what some aggregators list as 'Fairplay 100M/100K' — both refer to this HPRS event in Como/Park County.

  Also offers 19 mi, 10 mi

  ComoFairplay / South Park
  100 mi100K50 mi60K
• JUL 182026

  Last Mountain Man Standing

  ConiferDenver Metro & Foothills
  BackyardBackyard · 4.10 mi loop
• JUL 182026

  Powderhorn Mountain Ultra & Vert Challenge

  Powderhorn Resort (on the Grand Mesa).

  Also offers Vertical challenge (10K loop, 1,546 ft gain)

  MesaMountains / Western Slope
  Timed12-hr6-hr
• JUL 182026

  Silverton Alpine Marathon & 50K

  Alpine Loop; high point 12,930 ft at California Pass.

  Also offers Marathon, 8 mi

  SilvertonSan Juans
  50K
• JUL 19–212026

  ★TransRockies Run: Pass to Pub

  3-day stage race from Leadville to Red Cliff; crosses Hope Pass and the Continental Divide. Replaced the discontinued multi-day TransRockies Run format. Capped at 500 runners.

  Leadville to Red CliffCentral Mountains / Sawatch
  Stage51 mi · 3-day35 mi · 3-day
• JUL 24–252026

  ★Never Summer 100K & 60K

  Never Summer Mountains / Medicine Bow Mountains border; near RMNP; ~14,500 ft gain; high point North Diamond Peak (11,852 ft). Western States qualifier for 100K finishers under 23 hrs; sells out yearly.

  GouldMountains / Western Slope
  100K60K
• JUL 252026

  Box Canyon Trail Races

  Climbs from town past Bridal Veil Falls to ~13,000 ft. Ultra-adjacent event (30K is below the standard 50K threshold); grouped with Telluride-area ultra race weekends.

  Also offers 10 mi

  TellurideSan Juans
  30K
• JUL 252026

  Creede 50/100

  San Juans; climbs above 12,000 ft; 20,000+ ft gain; Continental Divide singletrack; start/finish Basham Park. 100-runner cap; USFS permitted; self-reliant ethos. Not the same event as Creede Mountain Run (different organizer, different history).

  CreedeSan Juans
  100 mi50 mi
• JUL 252026

  Pikes Peak Ultra

  Foothills/mountain terrain beneath Pikes Peak; longer courses summit Mt. Rosa. Considered a more approachable Front Range ultra.

  Also offers 30K, 20K

  Colorado SpringsColorado Springs / Pikes Peak
  50 mi50K
• August
• AUG2026

  San Juan Softie 100

  San Juan Mountains region; less technical variant of the area's high-mountain 100-milers. Featured on the curated UltraSignup Colorado list.

  DurangoSan Juans
  100 mi
• AUG 12026

  Aspen Backcountry

  Out-and-back to McNamara Hut; Elk Mountains backcountry singletrack above 10,000 ft. CORSAR card required.

  Also offers Marathon, Half

  AspenMountains / Western Slope
  50K
• AUG 12026

  Sheep Mountain Trail Runs

  300-runner cap; 50K distance added 2018.

  Also offers Half

  FairplayFairplay / South Park
  50 mi50K
• AUG 15–162026

  ★Leadville Trail 100 Run

  aka 'Race Across the Sky'. Out-and-back on Colorado Trail & dirt roads; climbs Hope Pass (12,532 ft); ~15,744 ft total climb. Western States/Grand Slam qualifier; 30-hr cutoff.

  LeadvilleCentral Mountains / Sawatch
  100 mi
• AUG 22–232026

  ★Telluride Mountain Run

  High San Juans above Telluride; above 13,000 ft; Mile-and-a-Half-of-Sky ridge; Telluride Peak (13,509 ft). Founded by Dakota Jones as a 38-miler. Exact 2026 distance lineup should be confirmed with organizer.

  Also offers Hill Climb & shorter options historically offered

  TellurideSan Juans
  100K40 mi
• AUG 292026

  Continental Divide Trail Run

  Steamboat Ski Area base; Continental Divide; Mt. Werner area.

  Also offers 16 mi, 8K

  Steamboat SpringsMountains / Western Slope
  50K
• AUG 292026

  Rock Hawk Trail Races

  Also offers 25K, 10K, 5K

  Castle RockDenver Metro & Foothills
  50K
• September
• SEP2026

  Ouray 50 Mile Endurance Run

  San Juan Mountains. Sister event to the Ouray 100; no longer a UTMB qualifier (stopped 2022).

  OuraySan Juans
  50 mi
• SEP 52026

  Creede Mountain Run

  Community race; distinct from the Tempest Adventures Creede 50/100 (different organizer, different history).

  Also offers 22 mi, 12 mi, 2 mi fun run

  CreedeSan Juans
  50K
• SEP 52026

  Raising the Barr

  Lakeside loop course; solo and relay options.

  BrightonDenver Metro & Foothills
  Timed12-hr6-hr
• SEP 52026

  The Grand Traverse (Mountain Run)

  Point-to-point across the Elk Mountains. Companion event to the winter Grand Traverse ski race.

  Crested ButteMountains / Western Slope
  40 mi
• SEP 52026

  ★The Sneffles Round ("Sneffelupagus")

  ~43,000 ft climb; ~34 peaks including 14er Mt. Sneffels; ~70% off-trail; self-navigated. Free entry; applicants vetted for mountaineering/routefinding skill; ~35-runner cap; 100-hr limit.

  OuraySan Juans
  ~75 mi
• SEP 11–122026

  American Heroes Run

  1.05-mi loop. Timed event; '100 mi' option is a goal distance within the timed format, not a fixed-distance race.

  Also offers 9-hr timed, 6-hr timed

  LongmontDenver Metro & Foothills
  Timed100 mi timed24-hr
• SEP 122026

  Devil on the Divide

  Exceeds 13,000 ft; 6,500+ ft climb; 80% of course above 10,000 ft. Requires prior ultra experience for the 50K.

  Also offers 22K

  Empire / Idaho SpringsDenver Metro & Foothills
  50K
• SEP 122026

  Snow Mountain Ranch Trail Running Festival

  Snow Mountain Ranch YMCA property.

  Also offers 33K, Half, 10K, 5K

  Granby / Grand LakeMountains / Western Slope
  50K
• SEP 18–192026

  ★Run Rabbit Run

  Routt National Forest; ~22,000 ft gain (100 mi) / ~9,000 ft (50 mi). 'Hares vs. Tortoises' staggered-start format. $100,000+ overall purse, $20,000 to each 100-mile winner — largest payout of any US ultra. ~$600,000 donated to charity.

  Steamboat SpringsMountains / Western Slope
  100 mi50 mi
• SEP 192026

  Beulah Challenge and OverIt Series

  Beulah Valley. 32 miles (just above the 50K threshold).

  Beulah ValleySouthern Colorado
  32 mi
• SEP 25–272026

  Red Feather Trail Jamboree

  Also offers Half

  Red Feather LakesNorthern Front Range
  50 mi50K
• SEP 262026

  24 Hours of Palmer Lake

  0.82-mi loop at 7,240 ft.

  Palmer LakeColorado Springs / Pikes Peak
  Timed24-hr
• SEP 262026

  Crested Butte Ultra

  Gunnison National Forest singletrack. Fall-foliage timing.

  Also offers 35K

  Crested ButteMountains / Western Slope
  50 mi55K
• SEP 26–272026

  Estes Epic Ultra Run & MTB Race

  Combined running + MTB weekend event.

  Also offers 15 mi

  Estes ParkEstes Park / RMNP
  50K
• SEP 26–272026

  ★Sangre de Cristo Trail Festival

  Rainbow Trail beneath the Sangre de Cristo peaks. Widest distance range of any CO ultra event: 50K through 200 mi.

  Also offers Shorter options

  WestcliffeSouthern Colorado
  200 mi100 mi100K50 mi+1
• SEP 262026

  West Line Winder

  ~4,000 ft climb near the Collegiate Peaks.

  Buena VistaCentral Mountains / Sawatch
  50K
• SEP 262026

  WILD Wahatoya Runs

  Views of the Spanish Peaks.

  Also offers Half, 8 mi

  La VetaSouthern Colorado
  50K
• SEP 272026

  Race The Ranch Snowshoe Ultra

  Also offers 25K, 5K

  GranbyMountains / Western Slope
  50K
• October
• OCT 32026

  Above the Clouds Ultra

  Starts/finishes at Woodland Park Middle School. ~4,137 ft gain on the 50K; ascends Lovell Gulch to Rampart Range Road, circles Rampart Reservoir; Pikes Peak views.

  Also offers 10K

  Woodland ParkColorado Springs / Pikes Peak
  50K
• OCT 32026

  Sage Burner Trail Races

  Hartman Rocks high-desert sagebrush terrain (near Gunnison). A contrast to CO's typical alpine ultras.

  Also offers 28K, 15K

  GunnisonMountains / Western Slope
  50K
• OCT 3–42026

  ★The Bear Chase

  Bear Creek Lake Park, Lakewood. 100K added 2013; beginner-friendly; benefits Lakewood open space.

  Also offers Half, 10K, 5K

  LakewoodDenver Metro & Foothills
  100K50 mi50K
• OCT 102026

  Rocky's Backyard Ultra

  Trails bordering Rocky Mountain National Park, at the YMCA of the Rockies; ~500 ft gain per loop. $1,000 cash prize + buckles for 100-mile finishers.

  Estes ParkEstes Park / RMNP
  BackyardBackyard · 4.17 mi loop
• OCT 172026

  Bobcat Trail Race

  Palmer Park sandstone/mesa terrain.

  Also offers 25K, 10K, 5K

  Colorado SpringsColorado Springs / Pikes Peak
  50K
• OCT 172026

  Indian Creek Trail Runs

  Pike National Forest foothills south of Denver.

  Also offers 15 mi, 8K

  Pine / SedaliaDenver Metro & Foothills
  50 mi55K
• OCT 242026

  Bridge Burner Ultra

  Royal Gorge Mountain Park. The 35-mi loop crosses the Royal Gorge Bridge.

  Also offers 35K, 10K

  Canon CitySouthern Colorado
  35 mi50K
• OCT 31 – NOV 12026

  Colorado 24 Hour Run

  Flat one-mile loop.

  Also offers 6-hr

  Fort CollinsNorthern Front Range
  Timed24-hr12-hr
• November
• NOV 72026

  Kessel Run Ultra

  Desert terrain near Colorado National Monument; Zippity-Do-Da singletrack. Camping available on-site.

  Also offers 20 mi, 10 mi

  FruitaMountains / Western Slope
  50 mi40 mi50K
• NOV 212026

  Colorado Cold Rush Ultra

  Bear Creek Regional Park, High Drive, Gold Camp Road; ~9,000 ft. Winter conditions likely (snow/ice).

  Also offers Half, 10K

  Colorado SpringsColorado Springs / Pikes Peak
  50K
• December
• DEC 52026

  Sawmill Trail Runs

  Staunton State Park. Started as an informal 'Fat Ass' event in 2013; became an official race in 2017; moved to Staunton in 2021.

  Also offers 16 mi, 8 mi

  PineDenver Metro & Foothills
  50K
• No date
• TBD2026

  Golden Gate Dirty 30

  DiscontinuedPermanently cancelled. Kept on the list so the record is complete.

  Golden Gate Canyon State Park. Official site (dirty30.org) states: 'Dirty 30 is permanently Cancelled.'

  Golden Gate CanyonDenver Metro & Foothills
  50K

Nothing on the list matches all of that. Loosen a filter — or switch onSub‑50K if you're after something shorter.