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Sean O'Brien 100K

Calabasas, United States • 31 Jan 2026

Event overview

The Sean O'Brien trail races take place on Saturday, January 31, 2026, in Calabasas, California. The event base is listed at 1925 Las Virgenes Road, Calabasas, CA. The 100k distance is designated as a 2026 Western States 100 (WS100) qualifier. The organizer’s page notes the event is currently sold out and that a waitlist is available.

Distances and registration

  • 100K
  • 50 Miler
  • 50K
  • Marathon (26.2)
  • 30K

Registration for the event closes on Saturday, November 15 at 11:59 PM PT. The event listing references course views at Mile 7 and Mile 15. Visit the organization's website for the most recent information.

United States California Calabasas

Race information

Website Registration
100 km
100k
50 mi
50 Miler
50 km
50k
26 mi
26.2
30 km
30k
Visit the organization's website for the most recent information.
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