O'brien Trail Races
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About the race
The O'Brien Trail Races take place at William O'Brien State Park in Marine on Saint Croix, Minnesota. The event is organized by True North Adventures and offers multiple trail distances held at the park visitor center. Parking and packet pickup are at the Visitor Center lot inside the park.
Distances offered:
- 50K : two 25k loops using the upper section, south section, and Jackson Meadows.
- 25K : single 25k course; course details to be determined.
- 10K : two laps of the 5k course on wide grass trails.
- 5K : wide grass trails with one large hill and a flat finish.
Aid stations and cutoffs vary by distance. The 50K uses four aid stations per loop and has a nine hour finish cutoff; the 25K lists four aid stations and a five hour cutoff. The 5K and 10K have no aid stations and a two hour finish cutoff. Drop bags are allowed at the start/finish area only. Awards are given to the top three male and female finishers in the 50K and 25K; the 5K and 10K do not have awards or included race shirts. All finishers will receive an 8.5 x 11 full color print of the event logo.
General event notes: no external music is allowed during the race without headphones, restrooms are available inside the Visitor Center, and post-race food and refreshments are provided. Online registration opens in late November 2025 and runs through late September 2026 with on-site race day registration available for an additional fee. There are no refunds or entry transfers. If the event is forced to shut down, races will convert to virtual events and race shirts and numbers will be mailed after the event. Visit the organization's website for the most recent information.
