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. 

SUNDAY, SEPT. 29, ROAD AND TRAIL IMPACTS: 

The Marathon, Half Marathon, 10K, and 5K courses will be active between 8 a.m. and 3 p.m. on Sunday Sep. 29. View an interactive map of the course.

County Closures: 

• Valmont Rd. will be closed westbound at Butte Mill Rd. from 7 a.m. to 9 a.m.   Westbound Valmont Rd. traffic will be diverted south at Butte Mill Rd. to Arapahoe Ave. 

• N 61st St./N. 63rd St. will be closed southbound between Jay Rd. and Valmont Rd. from 7 a.m. to 9:30 a.m. 

• N 63rd St. will be closed northbound between Jay Rd. and Gunbarrel Ave./Nautilus Dr. from 7 a.m. to 9:30 a.m.  Southbound 63rd St. remains open for Notting Hill Gate resident ingress/egress.  Twin Lakes residents: Please use Spine Rd. for ingress/egress until 9:30 a.m. and expect delays. 

• Jay Rd. will be closed eastbound between Spine Rd. and 63rd St. from 7 a.m. to 1 p.m., westbound Jay Rd. will remain open between 63rd St. and Spine Rd. for local access only. 

• Jay Rd. will also be closed westbound between 63rd St. and 75th St. from 7 a.m. to 12:30 p.m.   Eastbound Jay Rd. between 63rd St. and 75th St will remain open from 9 a.m. for local resident access only. Before 9am, Jay Rd. residents in this stretch should use 75th St. and Jay Rd. for ingress and egress. 

• N 75th St. will be closed southbound from Lookout Rd. to Jay Rd. from 7 a.m. to 12:30 p.m. 

• Lookout Rd. will be closed westbound between 75th St. and 95th St. from 7:30 a.m. to noon.  Eastbound Lookout Rd. remains open for local access.3 

• N 79th St. will be closed northbound between Lookout Rd. and Niwot Rd. from 7:30 a.m. to noon.  Southbound 79th St. remains open for local access. 

• N 57th St. will be closed northbound from 7 a.m. to 1 p.m.  Residents may access via N 57th. St & Jay Rd., traveling southbound and exiting via Independence Rd.  Independence Rd. will be closed eastbound from 7 a.m. to 1 p.m.

The following multi-use paths will remain open, but will have heavy runner traffic: 

• Along the west side of 75th St. between Lookout Rd. and Jay Rd. from 9 a.m. to 1 p.m. 

• Along the north side of Niwot Rd. between 79th St. and 95th St. from 8:30 a.m. to 11:30 a.m. 

City of Boulder Closures: 

• Pearl St./Pearl Pkwy. will be closed to all traffic between 15th Street (east end of Pearl St. Mall) and 55th St. from 7 a.m. to 9:30 a.m.    

• Mapleton Ave. will be closed westbound from Folsom St. to 14th St. from 7:30 a.m. to 2:30 p.m. 

• 14th St. will be closed to all traffic between Mapleton Ave. and Pearl St. from 7:30 a.m. to 2:30 p.m.   14th St. will also be closed between Walnut St. and Spruce St. from 6 a.m. on Friday, Oct. 8 through 7:30 p.m. on Sunday, Oct. 10. 

• 23rd St. will be closed to all traffic between Mapleton Ave. and Pearl St. from 7 a.m. to 11 a.m. 

The following multi-use trails will remain open, but will have heavy runner traffic: 

• Along the west side of 75th St. between Lookout Rd. and Jay Rd. from 9 a.m. to 1 p.m. 

• Cottonwood Trail between 47th St. and Independence Rd. from 7:30 a.m. to 1:15 p.m. 

• Wonderland Creek Path between 47th St. and Goose Creek Path from 7:30 a.m. to 1:30 p.m. 

• Goose Creek Path between Folsom St. and Pearl Pkwy. from 7 a.m. to 1:45 p.m. 

Information and Event Contacts

If you have questions or concerns, please visit the Boulderthon event website, or email community@boulderthon.org. You may also contact John Holste, Boulder County Special Events Coordinator at jholste@bouldercounty.gov or Justin Greenstein, City of Boulder Special Events Coordinator at greensteinj@bouldercolorado.gov.