Old-school cross-country style courses with creek crossings and bale jumps. Youth races 1k - 4k. All-ages 5k. Individuals and teams.

The Fall Series consists of four trail races in four different city/county parks. The trails range from well-maintained to rocky with tree roots. Each event is a unique challenge at a different distance, getting longer as the series progresses.

Join us for The Avery Fall 5k @ Avery Brewing on October 19, 2025, for a 5k-ish, fun run event that starts and ends at this awesome taproom in Boulder. Run, walk, jog - whatever goes! Complete the course and celebrate with us and a FREE, local craft brew at the finish line. Start windows […]

The 5K Fun Run, hosted in partnership with Lexipol and Axon, will take place in the heart of downtown Denver’s Civic Center Park. This signature event invites public safety professionals, supporters, and community members to start their day with purpose, connection, and movement. Participants will enjoy a scenic route through Denver’s civic and cultural core—surrounded […]

Lace up and join us for the IACP 5K Fun Run at the 2025 International Association of Chiefs of Police Conference in Denver! This lighthearted, non-competitive run is your chance to kick off the day with fresh air, great views, and even better company. Whether you’re a seasoned runner or just in it for the […]

The University of Denver's Annual Crimson Classic 5K Run/1.5 Mile Walk will take place on Carnegie Green Lawn. Music, stretching, and snacks will start at 2:15pm. The focus of the Crimson Classic is to celebrate wellness and to bring together our community. This is a free event! Please join us for a selection of wellness […]

Canyonlands 100K, 50 Mile, 50K, Marathon, Half Marathon, and 15K Canyonlands Ultra starts and finishes at the Behind the Rocks Trail, along the border of the Behind the Rocks Wilderness Study Area. Moab's last hidden gem; its tall standing Navajo Sandstone domes and fins can be seen from many places along the course. From smooth double […]

This single loop 50k starts in the historic mining town of Canon City, Colorado. Runners' journeys will begin along the beautiful Arkansas River and travel through the historic granite blasted tunnels along Tunnel Drive. From here, runners will begin their steep climb to the highest point of the course at 7,109’ feet. At the top […]

Run the original Bear Creek Lake Park trail race - the Beware the Bear Trail Races - on October 17th. This trail race consists of a 14.2K or a 5K. Or do them both with the double! There is also a kids 1K.

The Race to Cure Sarcoma (RTCS) is the premier run/walk series in the United States, focused on raising awareness, providing education, and research funds for sarcoma. Each year, the Sarcoma Foundation of America (SFA) hosts more than (20) RTCS events across the country. We provide a unique space in the sarcoma community where patients, survivors, their friends, […]

Join the Apex Park and Recreation District Foundation for the inaugural Trick or Trot 5K! Runners and walkers of all ages and abilities are all welcome to join us for this Halloween celebration. Dress in your Halloween best for a chance to win prizes for the costume contest. There will be a separate 1-mile Trick […]

A relatively new event to close out the Steamboat Springs Running Series season, bringing people of all ages together to celebrate Halloween in a safe, sober and fun way. The Foundry Treatment Center provides an opportunity for lasting recovery through an integrative body, mind and spirit treatment program. Comfortably located in the majestic Rocky Mountains […]

Get ready to lace up your sneakers (or your costume!) for Almost Home’s first-ever Spooky Sprint 5K! Join us on Saturday, October 25, 2025 at Margaret Carpenter Park in Thornton for a morning full of fun, community spirit, and impact. Whether you’re running, walking, or choosing to “sleep in”, every registration helps Almost Home provide […]

Our annual "spooky themed" race starts at the Palmer Lake Regional Recreation Area.  We head down the scenic Santa Fe Trail for a bit then turnaround and finish with a lap around Palmer Lake.  This is sure to be a fun day for everyone!  Our Kids Monster Dash Fun Run is for kids 12 and […]

Colorado's Favorite Halloween Runs....Each year the Theme Changes!! 2025 brings...SCARY CLOWNS / Circus Theme! Our best theme yet. Saturday Race is in Denver at 9:30am... then Sunday is in Louisville at 3:00pm on trails. This festival on Sloan's Lake, brings scary music, tons of Blow Ups, Carnival Games and Scary Clowns. The 5k and 10k […]

The world-famous Eerie Erie is a Halloween-themed 5k and 10k race that runs through historic downtown Erie and takes advantage of our beautiful trail system that weaves along the Coal Creek open space areas. The 10k passes by scenic Pleasant Hill Cemetery with panoramic views and where friendly spirits can’t wait to visit this year’s […]

This Halloween, join us for a spooky 5k or 1 mile loop through the Pioneer Cemetery in Idaho Springs!!  Try for a PR or take a leisurely stroll as you trick or treat with the ghouls in the graveyard. DON'T FORGET TO DRESS UP! Our Halloween costume contest gives you even more reason to rock […]

Join us for The Boos & Brews Halloween 5k @ Number Thirty Eight on October 25, 2025, for a 5k-ish, fun run event that starts and ends at this awesome taproom in Denver. Run, walk, jog - whatever goes! Complete the course and celebrate with us and a FREE, local craft brew at the finish […]

Get ready to lace up your running shoes and unleash your spooky spirit at the Redrum Costume Fun Run 2025! Join hundreds of ghosts, goblins, superheroes, and wacky characters as we dash through the heart of downtown Greeley in a festive 3K that’s more about fun than speed. This family-friendly event welcomes all ages and […]

Come one, come all! And join us in the "Quick Draw @ McGraw" 2 Mile Trail Run, organized and hosted by CRATES Colorado and benefitting McGraw Memorial Park. This challenging trail course located directly south of the Keystone Bridge located inside McGraw Park will give runners of all skill levels a true test of their […]

Costume up and bring your family and friends, we will haunt the town on our 5k route along the river while taking in the beautiful fall colors followed by a big costume contest, seasonal brews, hot chocolate and fun fitness games. Website link: https://grandvalleybrewruns.com/kannah-creek-brewing-company/ FB event page: https://www.facebook.com/events/737334659137680

This eerie evening race winds through a chilling course at the YMCA of Pueblo. The thrilling Halloween themed race is perfect for all ages and fitness levels. Recommended for those who want to have a hauntingly good PR. The best part of Spooky Sprint is you get to wear your costume! Whether you’re running as […]