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October 5, 2021

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Boulderthon Marathon and Half Marathon in Boulder County on Sunday, Oct. 10, 2021

Residents and travelers in the race area should plan for detours and delays


Boulder County, Colo. - The Boulderthon Marathon and Half Marathon will be held in Boulder County on Sunday, Oct. 10, 2021. Here is what you can expect when traveling through the area.

All community members will have access to their homes but may encounter delays and should follow recommended detours. If you are traveling through the area during the event please pay close attention to the Boulder County Sheriff, City of Boulder Police and traffic marshals to ensure safety for runners and travelers alike.

View an interactive map of the course, or more information and community impacts on the event website.

Road and Trail Impacts

The course will be active between 8 a.m. and 3 p.m. on Sunday, Oct. 10.

County Closures:

  • Niwot Rd./Neva Rd. will be closed to westbound traffic from 8:15 a.m. to 11:45 a.m. Eastbound traffic will remain open to allow local access. Lake Valley Estates residents may travel westbound on Neva Rd. after 10:30 a.m. to access US 36.
  • N. 51st/55th Streets will be closed to vehicular traffic from Jay Road to Niwot Road except to residents from 8:30 a.m. to 1 p.m. Residents may access via 47th & Jay Rd. or 55th & Jay Rd., no access from Diagonal Highway.
  • Jay Rd. will be closed to vehicular traffic from CO 119/Diagonal Highway to 47th St. from 9 a.m. to 1:15 p.m. Residents may access via 47th & Jay Rd., no access from Diagonal Highway.

City of Boulder Closures:

  • 47th St. will be closed to northbound traffic from the Pleasant View Soccer Fields to Jay Rd. from 9:15 a.m. to 1:15 p.m. Southbound will remain open to traffic.
  • Pearl St. will be closed to all traffic between 15th Street (east end of Pearl St. Mall) to 17th Street from 6 a.m. to 6 p.m.
  • 15th St. will be closed to all traffic between Lawry Lane and Spruce St. from 6 a.m. to 6 p.m. Access to the 15th Street Parking Garage will remain open.
  • 14th St. will be closed to all traffic between Walnut St. and Spruce St. from 6 a.m. on Friday, Oct. 8 through 6 p.m. on Sunday, Oct. 10.

Athlete/Spectator Information

Shuttles to the start will be provided to all runners from Downtown Boulder. Shuttles are for registered runners only; no friends or family will be permitted. Shuttle service begins at the Boulder High School parking lot at 5:30 a.m. There will also be Runner Drop-off (via Uber/Lyft, or a friend or family) at Boulder Reservoir. Please utilize Downtown Boulder parking garages, there is no spectator or participant parking at the Boulder Reservoir on Race Day and all runners must board the shuttle at Boulder High School or be dropped off at Runner Drop-Off. In accordance with federal mandates, masks are required on all Boulderthon shuttles.

Additional Questions or Concerns?

If you have questions or concerns, please email community@boulderthon.org, or contact John Holste, Boulder County Special Events Coordinator at jholste@bouldercounty.org.

Boulderthon Marathon course map, Oct. 10, 2021


Boulderthon Half Marathon course map, Oct. 10, 2021Boulderthon road impacts list, Oct. 10, 2021