Thank you for choosing to participate in the Endurance Race Series, Colorado's Largest Trail Race Series. We know there are many events out there to choose from, so your participation is much appreciated. 

Aside from individual race registration to each of our races, we also offer a Season Pass (VIP Package), and a Pick 6 option. For more information on either of these additional options please click on the link below.

​For individual race registration click on the race logo. 

Happy Trail Running!!


ALL pre-registered runners will receive a gender specific T-shirt (tech tee) upon packet pickup. When registering for your event online you will have the opportunity to select the correct shirt size.

Important-Only those people that PRE-register for an event will be guaranteed to receive a T-Shirt with their registration, while ALL packet pickup and race day registrations will be asked to wait until after the designated event to pick up their race shirt. Please note, that race day registrants will not be guaranteed the correct size shirt if any at all. Thank you for understanding this policy, as we want to make sure those runners that register early do receive the shirt they requested.  
 It is our recommendation that you complete online registration no later than 1 week prior to that event to be guaranteed a shirt of your choosing.

ALL FINISHERS, regardless of distance will receive a medal.

If you register for a specific race distance and need to upgrade or downgrade, you may do so by contacting our staff before the registered event. 

  • $30 Upgrade Fee is required for 10k to Half
  • $15 Upgrade fee is required for 5k to 10k
  • No refunds will be given for downgrading

Season Pass holders that finish all 10 races will receive a special "SEASON PASS AWARD" and "SEASON PASS MEDAL" at the conclusion of the series.

Del Dios Trail Race
Snow Mountain Ranch Trail Race
Black Mountain Trail Race
Louisville Trail Race
ERS events facebook page

Colorado Races

Carmel Valley Trail Race
Denver Trail Race

California Races

Registration Information