Registration for Boulderthon 2023 is now open! After nearly tripling in size and selling out last year, Boulderthon has instituted a new 5,000 runner cap and is expected to sell out again this year. Register today.
aerial view of Boulder Colorado mountains


When we pushed back and secured April 25th, 2021 as our new Race Date for the Boulderthon, we never expected that we'd ever have to send this email again. We are incredibly disappointed, and have no choice but to cancel our in-person edition on April 25th, 2021, moving to Virtual only, due to ongoing group gathering restrictions, and the continuous covid impact in our community.

We could not be more grateful for your support, and like all of us, never expected to have to face this in our first year as we launched our community's new signature Boulder Marathon series. As I'm sure many of you know from our correspondence together and the amazing training runs you have shared with us, please know that this decision did not come lightly, and the Boulderthon team has truly explored every angle and possible format to attempt to bring our new race series and downtown marathon experience to life this Fall.

Despite the huge strides in progress against covid, next month has simply proven to be too soon to produce this marathon race with a downtown finish. After all the long hours & best efforts of our team over the last few months, in consultation with our closest partners at the City of Boulder, Boulder County, and CDPHE, we are so sorry to have to share that there is no path forward to produce the first edition of our race in April.

We again want to reiterate that the Boulderthon team could not be more grateful for all the support we have received from our running community, and know that when we are finally able to run together in October, it will truly be that much sweeter, and an absolutely amazing, inspirational, and beautiful moment for us all.