O'brien Trail Races
Marine on Saint Croix, United States • 26 Sep 2026
Event overview
O'Brien Trail Races take place on Saturday, September 26, 2026 at William O'Brien State Park in Marine on Saint Croix, Minnesota. The event offers multiple trail distances and includes both longer trail loops and shorter grass-trail races. The start and finish area is at the park Visitor Center, with parking in the Visitor Center lot and restrooms inside the Visitor Center.
Distances
- 50K
- 25k
- 10K
- 5k
Courses and cutoffs
The 50K is run as two 25k loops using the park upper section, south section, and Jackson Meadows. The 50K has four aid stations per loop, drop bags are allowed only at the start/finish area, and there is a 9-hour overall cutoff; runners must begin the second loop by midday. The 25k has four aid stations and a 5-hour cutoff. The 10K runs the 5k course twice. The 5k and 10k use wide grass trails with one large hill and a flat finish; these shorter races have no aid stations and a 2-hour cutoff.
Registration, fees and services
Online registration opens 11/28/2025 and runs through September 2026; race day registration is available with higher fees. Race shirts are optional as an entry add-on. Packet pickup is race morning only. Post-race food and aid station items include water, sports drink, cookies and other snacks. The event has a no-refund, no-transfer, no-deferral policy. If the event is canceled for public-health or similar reasons, it will move to virtual format and shirts and numbers will be mailed after the event. Visit the organization's website for the most recent information.