O'brien Trail Races
Marine on Saint Croix, United States • 26 Sep 2026
Event
The O'Brien Trail Races take place at William O'Brien State Park in Marine on Saint Croix, Minnesota. The race center is at the park Visitor Center; parking is in the Visitor Center lot. The event date is Saturday, September 26, 2026. Distances offered include:
- 50K
- 25k
- 10K
- 5k
Courses and race logistics
The 50K is two 25k loops using the upper section, south section of the park, and Jackson Meadows. The 50K has four aid stations per loop, drop bags are allowed at the start/finish area only, and there is an overall time limit of nine hours; runners must reach the start of the second loop within four hours. The 25k course is noted as to be determined, with four aid stations and a five-hour cutoff. The 10K is the 5k done twice; the 5k and 10k run on wide grass trails with one large hill and a flat finish. The 5k and 10k have a two-hour finish cutoff, no aid stations, no awards, and no race shirts. All finishers of the 5k and 10k receive a full-color 8.5 x 11 print of the current year logo.
Aid stations are expected to offer water, sports drink, cookies, and other items. Bathrooms are available inside the Visitor Center.
Registration and policies
Online registration opens on 11/28/2025; race-day registration is available. Entry fees vary by race and registration date. Packet pickup is race morning only. There are no refunds, no entry transfers, and no deferrals. If the event is forced to shut down, it may be converted to a virtual event with shirts and bibs mailed after the event. Visit the organization's website for the most recent information.