Marathon, Half Marathon, Urban 10 Miler, Marathon Relay: online registration closes Wednesday, May 14th at 11:59pm. Registration reopens at the Expo Friday, May 16th and Saturday, May 17th.

Colfax 5K: online registration closes Wednesday, May 14th at 11:59pm. Then you have 2 choices for registration: Friday, May 16th at the Expo, or Saturday, May 17th at City Park – starting at 7:30am before the race.

Girls On The Run 5K registration is open online until Wednesday, May14th at midnight, and at the expo on Friday.  Race day registration and packet pick-up opens Saturday at 9:15am in City Park.

Registration for the 2 Day Challenge requires an athlete to run the Colfax 5K on Saturday and Full Marathon, Half Marathon, Urban 10 Mile or Marathon Relay on Sunday. For additional information, and to register, please click here.  This link addresses if you have not yet registered, or if you want to add the 5K to your registraition.  If you are running the Marathon Relay, register for the 5K and answer yes to the question are you running on Sunday.

If you are an elite runner, please visit the Elite Runner Program page.

Elite entry and prize money rules state to be eligible for elite entry, prize purse, bonus or to be eligible to set an event or course record at the Colfax Marathon, Half Marathon or Marathon Relay, an athlete must not be represented by coaches and/or agents who have had two or more athletes suspended or banned for the use of performance-enhancing drugs in the previous four years.

Yes. The marathon course is a Boston Marathon qualifier. All courses have been accurately measured and certified by USA Track & Field.

Yes. The Colfax 5K is a qualifier for the BolderBoulder. The course has been accurately measured and certified by USA Track & Field.

Race results will be posted on the Colfax Marathon website after the event. Previous race results are available on the Race Results page.

Yes. Please check back in late October.

Yes.  Shuttles will be available in 2025.  Shuttle information will be provided in the Fall.

Yes. The Post-Race Festival is located in Denver’s City Park “meadow area”, east of City Park’s pavilion and lake, and due west of the Denver Museum of Nature and Science after the race. Spectators, family and friends are welcome in this area. The party will feature live music, food and drinks, and the Charity Partner Village will showcase our Charity Partners.

Well-behaved dogs are allowed in the Colfax 5K. There will be waves allowing runners with dogs, joggers with dogs and walkers with dogs on Saturday, May 17th.   Runners with dogs should start in the back of their designated corral.

Dogs are NOT permitted during the Sunday, May 18th races.

Runner’s Edge of the Rockies marathon training program will lead the official pace teams for the Full & Half Marathon. (FULL: 3:15, 3:30, 3:40, 3:50, 4:00, 4:10, 4:20, 4:30, 4:45, 5:00, 5:15, 5:30, 5:45 and 6:00  HALF: 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 2:00, 2:05, 2:10, 2:15, 2:20, 2:25, 2:30, 2:35, 2:40, 2:45, 2:50, 2:55, 3:00, 3:15, and 3:25).

They utilize the SmartPacing “even energy” methodology, which is race course specific and designed to help you run a negative split for a stronger finish. Pacers will be at the expo answering questions and passing out pace bands.

The Colfax 5K is the only race in which we allow walkers. See details below for each race.

Please note: Sunday races cause significant road closures across metro Denver, and we must allow police to re-open roads to traffic in a timely manner, hence the need to set time limits.

Marathon: No. There is a 6 hour time limit (13:44 minutes per mile pace). If you fall behind this pace, you will be asked to stop for safety reasons. The time limit for each race begins when the final corral of your race crosses the start line. There is a sag wagon.

Urban 10 Miler: No. There is a 2.5 hour limit (15:00 minutes per mile pace). If you fall behind this pace, you will be asked to stop for safety reasons. The time limit for each race begins when the final corral of your race crosses the start line. Please note: there is no sag wagon available as this is a staggered start. As we feed into the marathon course, it is important not to slow the progress of the marathoners, who are on a 13:44 minutes per mile pace.

Marathon Relay:  No. There is a 6 hour time limit (13:44 minutes per mile pace). If you fall behind this pace, you will be asked to stop for safety reasons. The time limit for each race begins when the final corral of your race crosses the start line. There is a sag wagon.

Half Marathon:  No. There is a 3 hour 25 minute time limit (15:30 minutes per mile pace). If you fall behind this pace, you will be asked to stop for safety reasons. The time limit for each race begins when the final corral of your race crosses the start line. There is a sag wagon.

Colfax 5K: Yes. There is no time limit. This is the only race that you can have a stroller.

If you refuse to be picked up by the sag wagon, you will be immediately and officially disqualified and forfeit all your rights as a participant.

No. All Sunday races have a pre-race bag check. Any clothing left at the start, finish line or on the course will be donated to charity immediately.

Please note: Leg 1 of the Relay can use bag check. Legs 2-5 of the Relay do not have bag check.

The 5K does not have a bag check.

The Colfax Marathon continuously seeks to improve the weekend’s Green Footprint every year. The Colfax Marathon strongly encourages all of their suppliers to use recyclable products throughout the entire weekend. Recycling bins will be located throughout City Park, and cardboard is recycled. There is a recycle roll-off behind the scenes. Composting is done by staff behind the scenes. Clothing left at the start line is recycled, utilizing a current Colfax Marathon Charity Partner to help individuals in need throughout the local community. Post-race water system has been created to refill water bottles for both spectators and athletes. Athletes are encouraged to carpool to the events. RTD is provided for relay athletes to return to the start of the Relay or their car. All Urban 10 Milers receive an RTD pass to return to their car. As always, we are constantly reevaluating our program.

Road closure information will be provided in late spring.

Register early for the best prices! To view current pricing information, please visit our Race Pricing page.

Yes. You must be 16 years old to run the Marathon and 12 years old to run the Half Marathon, Marathon Relay or Urban 10 Miler on race day. The 5K is open to runners of all ages.

Yes. Registration changes are free on or before April 17th. Please click here to make your changes.

Changes made between April 18th and May 14th are $10. Please click here to make your changes.

After May 14th, all changes must be made at the Solutions Line at the Expo and are $15.

Relay team changes are explained in detail in the Relay Section.

For questions regarding: Finding your registration and dashboard please contact Race Roster here.  Please allow 3-5 business days for a reply.

To change race distance please see Q6 and Q7.

Please click here to confirm your registration on or before May 14th.

For questions regarding: Finding your registration and dashboard please contact Race Roster here.  Please allow 3-5 business days for a reply.

Yes. You may switch races to a shorter distance (i.e., from the Full to the Half), unless the race is sold out. You cannot transfer into a race that is sold out.

Registration changes are free on or before April 17th. Please email info@runcolfax.org to make your changes and be sure to enter a new anticipated finish time for your new distance.

Changes made between April 18th and May 14th are $10. Please click here to make your changes and be sure to enter a new anticipated finish time for your new distance.

After May 14th, all changes must be made at the Solutions Line at the Expo and are $15.

Please note: if you make your change after April  30th, we do not guarantee runner tracking will be appropriately switched to your new distance. Also, you may not be in the correct corral for your pace. Therefore, we strongly recommend, all changes be done before May 1st.

For questions regarding: Finding your registration and dashboard please contact Race Roster here.  Please allow 3-5 business days for a reply.

If a relay team wants to change from multiple runners to individual races or the 5K, please email info@runcolfax.org.

Yes. You may switch races to a longer distance (i.e., from the Half to the Full), unless the race is sold out. You cannot transfer into a race that is sold out.

You will be charged the difference of the current registration cost for the longer race. There is no additional fee for changes made on or before April 17th. Please email info@runcolfax.org  to make your changes and be sure to enter a new anticipated finish time for your new distance.

Changes made April 18th or and before May 14th are $10, in addition to the difference of the current registration cost for the longer race. Please click here to make your changes.

After May 14th, all changes must be made at the Solutions Line at the Expo and are $15, in addition to the difference of the current registration cost for the longer race.

Please note: if you make your change after April  30th, we do not guarantee runner tracking will be appropriately switched to your new distance. Also, you may not be in the correct corral for your pace. Therefore, we strongly recommend, all changes be done before May 1st.

For questions regarding: Finding your registration and dashboard please contact Race Roster here.  Please allow 3-5 business days for a reply.

If a relay team wants to change from multiple runners to individual races or the 5K, please email info@runcolfax.org.

The Colfax Marathon does not offer refunds for any reason. During registration, you can opt to pay for race insurance through a third party, which covers you for select health and other reasons.  Insurance must be purchased at the time of registration.  This option is open to paying registrants, but not offered to those using a deferral code.  The Colfax Marathon encourages runners to purchase this insurance. Fan Shield handles all claims and is a separate organization from the Colfax Marathon. To view all of the covered reasons for a refund, click here.

Relay Team Member Injuries:

If you have an injured relay team member, the best course of action is to replace that team member. *Corporate or Government Cup relay teams see below.*

Relay team member changes are free on or before April 17th. Please email info@runcolfax.org to make your changes.

Relay team member changes between April 18th and May 14th are $10. Please click here to make your changes.  It is $10 per form to make all the changes/additions to the runners on your team – whether you are changing or adding one runner or five runners. Make all your changes at once, as additional changes are $10 per form. These changes may not be reflected until the Expo. They will not show up on your team registration.

After May 14th, all relay team member changes must be made at the Solutions Line at the Expo and are $15.

If your entire team cannot run, the best course of action is to transfer your team to a new group of runners. This option is open to paying teams, but not offered to those using a deferral code.

You may transfer your registration to another group of runners on or before May 14th. There is a $40 fee. Please email info@runcolfax.org to make your changes.

After May 14th, all team transfers must occur at the Solutions Line at the Expo on Friday 16th, or Saturday, May 17th. The new team Captain/Coordinator must bring a letter from the original team Captain/Coordinator and a photo copy of the original Captain/Coordinator’s ID stating the intent to transfer to the new group. There is a $40 fee.

You cannot choose different shirt sizes. The shirt sizes originally ordered must be picked up, but the new athletes can request different sizes at the shirt exchange located at the Expo. However, we cannot guarantee shirt sizes.

For questions regarding: Finding your registration and dashboard please contact Race Roster here.  Please allow 3-5 business days for a reply.

*For Corporate or Government Cup teams: to be eligible for the Corporate or Government Cup you need five runners. If you change a runner, you must sub in another employee or a family member. Corporate and Government teams must be employees (or elected government officials), and up to two family members.*

For information on each specific race, such as start location, starting time, and more, please go to the Races page and visit the desired race page (Full, Half, etc.).

Please note: some races starts are at different times and locations, such as the Half Marathon (different time) and the Urban 10 Miler (different time and location). The sidebar on the right side of the race page will have more detailed information.

We will be using the latest timing technology for all runners. The timing tag is attached to the back of your race bib, so your time starts when you cross the Start Line. Relay team runners will be carrying and handing off a baton that has a timing chip inside it.

Yes. All runners will be timed. However, relay teams’ timing tag will be located in the relay baton. The baton will function the same way as the timing tags for all other runners. When you cross the start check points and the finish, be sure to have your baton out and no higher than chest-level. Relay runners will be timed for their individual leg.  The time will correspond to the relay leg and labeled accordingly.

Yes. You may move to a slower corral on Race Day, but you may not switch to a faster corral on Race Day. If you need to switch to a faster corral because your pace has increased since registration, you can change your estimated finish time for free on or before April 17th. Please email info@runcolfax.org to make your changes.

Changes made between April 18th and May 14th are $10. Please click here to make your changes.

After May 14th, all changes must be made at the Solutions Line at the Expo and are $15.

For questions regarding: Finding your registration and dashboard please contact Race Roster here.  Please allow 3-5 business days for a reply.

We’d love to have you volunteer! Please visit our Volunteer page. There are indoor and outdoor jobs available, and our primary volunteer days are Friday, May 16th, Saturday, May 17th and Sunday, May 18th.

Yes. All Sunday races have time limits. The time limit for each race begins when the final corral of your race crosses the start line.

Please note: Sunday races cause significant road closures across metro Denver, and we must allow police to re-open roads to traffic in a timely manner, hence the need to set time limits.

Marathon: There is a 6 hour time limit (13:44 minutes per mile pace). If you fall behind this pace, you will be asked to stop for safety reasons. There is a sag wagon.

Urban 10 Miler: There is a 2.5 hour limit (15:00 minutes per mile pace). If you fall behind this pace, you will be asked to stop for safety reasons. Please note: there is no sag wagon available as this is a staggered start. As we feed into the marathon course, it is important not to slow the progress of the marathoners, who are on a 13:44 minutes per mile pace.

Marathon Relay:  There is a 6 hour time limit (13:44 minutes per mile pace). If you fall behind this pace, you will be asked to stop for safety reasons. There is a sag wagon.

Half Marathon:  There is a 3:25 hour time limit (15:30 minutes per mile pace). If you fall behind this pace, you will be asked to stop for safety reasons. There is a sag wagon.

Colfax 5K: Saturday, there is no time limit. This is the only race that you can have a stroller.

If you refuse to be picked up by the sag wagon, you will be immediately and officially disqualified and forfeit all your rights and benefits as a participant.

Yes. Gatorade Endurance Formula will be on the Marathon and Half Marathon Course. The Gatorade Endurance Formula contains no artificial flavors or sweeteners and has a lighter taste for endurance athletes.

Yes. Honey Stinger is proud to be the Performance Nutrition Partner of the Colfax Marathon and Half Marathon!

Due to safety reasons, strollers are only allowed Saturday during the Colfax 5k.  Strollers are NOT permitted at the races on Sunday, May 18th.

The use of personal music devices is strongly discouraged at this race. To enjoy all our race has to offer and for the safety of all participants, Colfax Marathon encourages a headphone-free environment during the running of all races.
We believe your race experience and those around you will be greatly enhanced by leaving the headphones at home or in the car. Running headphone-free allows opportunities to develop camaraderie with your fellow runners and to enjoy everything the race has to offer. Plus, volunteers and spectators will be on course cheering you on and providing directions to help get you to the finish line.
Runner safety has always been, and will continue to be, a top priority for our event. Please be mindful of the other participants and respect the race personnel to ensure a safe and enjoyable race for everyone.

There is no official parking lot or designated parking areas on race day. We suggest you arrive early to find the best parking or have a friend drop you off.
Plan to arrive at least 1 hour prior to the published Start Time of your event at City Park. That is, plan to be in the vicinity of your marathon/marathon relay start corral 30 minutes before the start. Half Marathon participants should be in the vicinity of your start corral 30 minutes before your the start (you will be allowed to enter your corral once the marathon has cleared the start).
Parking for the Legs 2, 3, 4, and 5 runners for the Relay is at the start of the runner’s leg. Not at City Park. Click here for the marathon relay overview page.

Yes, for Sunday races. Bag check is available for the Marathon, Half Marathon, Urban 10 Miler, and Leg 1 of the Marathon Relay.  There is no bag check for Legs 2-5 of the Relay.

The Urban 10 Miler will have a bag check at the start of the 10 Miler at RMCAD (Rocky Mountain College of Arts and Design) until 10am. Please recognize there will be a time delay getting bags to the finish.

All bags will be subject to inspection.

There is no bag check for the 5K on Saturday.

For the Relay and Urban 10, RTD instructions will be available in early May.

Check out the Marathon Relay page for an overview.  Please check back at the end of April to view and print detailed relay instructions, including Relay exchange zone information.

Register online for the 2025 Colfax Marathon Relay on or before May 14th here, or register in person at the Solutions Line at the Expo Friday, May 16th, or Saturday, May 17th.

Yes.  All team members and shirt sizes must be entered before a team is allowed to pick up their packets.

Yes. Relay team changes are free on or before April 17th. Please click here to make your changes. *Corporate or Government Cup relay teams see below.*

Relay team changes between April 18th and May 14th are $10. Please click here to make your changes.   It is $10 per request to make all the changes/additions to the runners on your team – whether you are changing or adding one runner or five runners. Make all your changes at once, as additional changes are $10 per change. Late changes may not be reflected until the Expo. They will not show up on your team registration.

After May 14th, all changes must be made at the Solutions Line at the Expo and are $15.

You cannot choose different shirt sizes. The shirt sizes originally ordered must be picked up, but the new athletes can request different sizes at the shirt exchange located at the Expo. However, we cannot guarantee shirt sizes.

*For Corporate or Government Cup teams: to be eligible for the Corporate or Government Cup you need five runners. If you change a runner, you must sub in another employee or a family member. Corporate and Government teams must be employees (or elected government officials), and up to two family members.*

Yes. Relay team changes are free on or before April 17th. Please click here to make your changes. *Corporate or Government Cup relay teams see below.*

Relay team changes between April 18th and May 14th are $10. Please click here to make your changes.   It is $10 per request to make all the changes/additions to the runners on your team – whether you are changing or adding one runner or five runners. Make all your changes at once, as additional changes are $10 per form. Late changes may not be reflected until the Expo. They will not show up on your team registration.

After May 14th, all changes must be made at the Solutions Line at the Expo and are $15.

You cannot choose different shirt sizes. The shirt sizes originally ordered must be picked up, but the new athletes can request different sizes at the shirt exchange located at the Expo. However, we cannot guarantee shirt sizes.

*For Corporate or Government Cup teams: to be eligible for the Corporate or Government Cup you need five runners. If you change a runner, you must sub in another employee or a family member. Corporate and Government teams must be employees (or elected government officials), and up to two family members.*

Yes. If you registered as a Captain or non-running Coordinator, who paid for the entire team on or before April 17, you may view your information by logging on here. There, you can see all the runners on your team.

Please note: you are responsible for adding all the runners to your team(s). The individual runners will not be able to logon and see their registration or change their information. You will be able to make any additions or changes on behalf of your team for free on or before April 17th. Please click here to make your changes. *Corporate or Government Cup relay teams see below.*

Relay team changes between April 18th and May 14th are $10. Please click here to make your changes.It is $10 per request to make all the changes/additions to the runners on your team – whether you are changing or adding one runner or five runners. Make all your changes at once, as additional changes are $10 per request. These changes will not be reflected until the Expo. They will not show up on your team registration.

After May 14th, all changes must be made at the Solutions Line at the Expo and are $15.

You cannot choose different shirt sizes. The shirt sizes originally ordered must be picked up, but the new athletes can request different sizes at the shirt exchange located at the Expo. However, we cannot guarantee shirt sizes.

*For Corporate or Government Cup teams: to be eligible for the Corporate or Government Cup you need five runners. If you change a runner, you must sub in another employee or a family member. Corporate and Government teams must be employees (or elected government officials), and up to two family members.*

Please visit our Marathon Relay page, Corporate Cup Relay page or Government Cup Relay page.

Yes. The Captain will simply indicate the team type when registering the team, and then a separate question will ask about picking a Charity Partner. All athletes on a team have to run for the same charity. For more information, please visit our 2025 Charity Partners Program page.

Yes. We don’t track which of your runners are running specific legs.

Yes. We highly recommend that the captain and team runners attend the expo together for last minute planning with our ambassadors.

The captain can pick up the packet for the entire team. Individual team members can pick up their own packet.

An individual team member can pick up additional team member packets (including the entire teams’) if an Alternative Packet Pickup Form has been completed by their team members. Alternative Packet Pickup Forms will be available in early 2025.

2025 Expo details will be available in January.

Expo hours and details will be available in January.

Marathon, Half Marathon, Urban 10, and Relay participants are required to attend the Expo during expo hours to pick up their race packets and race shirts. There will be no race day packet pick up.

Relay teams are strongly encouraged to attend as a team!

5K runners can pick up their bib/shirt at the Expo on Friday, May 16, or at City Park on race morning.

We do realize there may be unavoidable conflicts, and you need to assign a different person to pick up your packet, or for captains, you need to pick a different person to pick up for the team. Alternative Packet Pickup Forms will be available in the spring.

No. Only service dogs are allowed into the Expo.

The expo will be at Empower Field at Mile High Friday, May 16th and Saturday, May 17th.  Expo details will be available in January.

Parking at the Expo is free. Expo details will be available in January.

We will have a separate shirt exchange table at the Expo. Exchange sizes are first come, first served and cannot be guaranteed.

You must bring your assigned bib number and photo ID.

Yes. Please visit our Volunteer page and sign up!

You will be sent your bib number via email race Wednesday evening week. Please bring this number with you to the Expo. However, if you forget your bib number, there will be a bank of iPads with bib information at the Expo.

Marathon, Half Marathon, Urban 10, and Relay participants are required to attend the Expo during expo hours to pick up their race packets and race shirts.  Expo details will be available in January.

Relay teams are strongly encouraged to attend as a team!

5K runners can pick up bib/shirt at the Expo on Friday, May 17, or at City Park on race morning.

We do realize there may be unavoidable conflicts, and you need to assign a different person to pick up your packet, or for captains, you need to pick a different person to pick up for the team. An Alternative Packet Pickup Form will be available here in March.

If you are an athlete looking for more information about running for charity, please visit our Run for a Nonprofit page for detailed information.

If you are a nonprofit looking for more information about being a Charity Partner, please visit our Charity Partners Program page for detailed information.

Attend one of our informational meetings! Find out more on the Charity Partners Program page.

We appreciate you running for our charities, so the changes are always free.

To add a charity partner on or before May 14, Please click here.

After May 14th, you can add your Charity Partner at the Solutions Line at the Expo.

Relay team Charity Partner additions are the same. All athletes on a team have to run for the same charity.

Yes, please visit our Charity Partners page for a list of our current Charity Partner.

The best idea is to encourage them to attend an introductory meeting. Send them this link.

You can also contact us with the organization name and a contact, if you have it. Send your message to charitypartner@runcolfax.org.

When registering, you’ll be asked, “Do you (or your team) plan to raise funds or awareness for one of our charity partners?” Use the drop down menu to select your charity. Your charity will contact you directly and let you know how to raise money for them.

If you choose to add a charity partner after registering, the change will always be free, as we appreciate our athletes running for our charities.

To add a charity partner on or before May 14th, Please click here.

After May 14th, you can add your Charity Partner at the Solutions Line at the Expo.

Relay team charity partner additions are the same. All athletes on a team have to run for the same charity.

Yes. Charity Partners can enter the Corporate Cup Non-Profit Division if the runners are all employees (up to 2 can be family members of employees). Please visit our Corporate Cup Relay page for further details.

If you are an athlete with a disability and have questions, please check out our Athletes with Disabilities page.