O'brien Trail Races

O'Brien Trail Races

O'Brien Trail Races take place at William O'Brien State Park near Marine on Saint Croix, Minnesota. The event offers multiple trail distances and uses park trails including sections called Jackson Meadows. Races start and finish at the park Visitor Center; parking is at the Visitor Center lot.

Distances offered:

• 50K: two 25k loops using the upper and south park sections and Jackson Meadows.
• 25K: 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.

The 50K uses two 25k loops, has four aid stations per loop, a first-loop maximum time of four hours, and an overall finish cutoff of nine hours. The 25K has multiple aid stations and a five-hour cutoff. The 5K and 10K have no aid stations. Finishers receive a full color print of the event logo.

Online registration opens on November 28, 2025 and runs through late September 2026; race day registration is available. Race shirts are optional and offered separately. Packet pickup is race morning only. Bathrooms are available inside the Visitor Center. There are no refunds and entries cannot be transferred or deferred. If the event is forced to shut down, it may convert to a virtual event and race materials will be mailed. Visit the organization's website for the most recent information.