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5K races in Boulder County (2026-27)

4 upcoming 5k races in Boulder County in the next 12 months. The next is Colleen De Reuck XC Classic on Saturday October 31 in Boulder, from $15.

All DenverDenver (40)Boulder County (4)Denver Suburbs (72)Foothills & Mountains (9)Fort Collins & Loveland (7)

• Sat31Oct

  Colleen De Reuck XC Classic

  Sat Oct 31 · 9:00 AM · Boulder · Boulder County

  1K3K5KTrail

  from $15
• Thu26Nov

  Alpine Bank Boulder Thanksgiving Day 5K

  Thu Nov 26 · 9:00 AM · Boulder · Boulder County

  5K

  from $40Goes up Nov 21
• Sun2May

  Emerge 5K

  Sun May 2 · 8:00 AM · Boulder · Boulder County

  5K

  Reg. closed
• Sat12Jun

  Alpha 5K Challenge

  Sat Jun 12 · 7:30 AM · Boulder · Boulder County

  5K

  Reg. closed