O'brien Trail Races
Always double-check with the organizer's website! This page may contain affiliate links.
About the race
The O'Brien Trail Races take place at William O'Brien State Park near Marine on Saint Croix, Minnesota. The event features trail races over several distances on park trails, with the start and packet pickup at the park Visitor Center and parking at the Visitor Center lot.
Distances include:
- 50K two 25K loops using the upper and south sections of the park and Jackson Meadows.
- 25K single loop course (details to be determined).
- 10K course composed of the 5K loop run twice.
- 5K short loop on wide grass trails with one large hill and a flat finish.
Aid stations, cutoffs, awards and entry fees vary by distance. The 50K has four aid stations per loop, drop bags at the start/finish area, and a total finish cutoff of nine hours; the first 25K loop must be completed within roughly four hours to continue. The 25K uses four aid stations and has a five-hour cutoff. The 5K and 10K have no aid stations, no awards, and a two-hour cutoff; all finishers receive a full-color 8.5 x 11 print of the event logo.
Online registration opens 11/28/2025 and runs through late September 2026 for most distances; race-day registration is available. Entry fees vary by distance and date, and there are no refunds, transfers, or deferrals. If the in-person event is canceled for public health or similar reasons, the races will convert to virtual and race shirts and bibs will be mailed after the event.
Additional notes: no external music without headphones, bathrooms in the Visitor Center, and post-race refreshments at the finish area. The event is organized by True North Adventures. Visit the organization's website for the most recent information.
