OBrien Trail Races

The OBrien Trail Races return to Marine On St Croix, Minnesota on September 26th, bringing together runners for a variety of challenging distances in William O'Brien State Park. The event offers four distinct race categories: the grueling 50K and 25K ultra runs starting early at 8:00 AM and 9:00 AM respectively, along with more accessible but equally scenic 10K and 5K routes that begin simultaneously at 9:00 AM. All races take place within William O'Brien State Park, which is located just off state highway MN-95 north of Marine On St Croix.
On race morning in September, runners will find the park's trails firm yet slightly soft underfoot due to natural conditions. The temperature averages around 19.5 degrees Celsius with a range from 14.7°C at its coolest to 24.3°C during peak warmth. Humidity tends to hover near 72%, and there is typically a light risk of precipitation, amounting to approximately 3.2mm over the course day. The morning breeze averages around 12 kilometers per hour with UV index levels reaching moderate at 3.5.
The OBrien Trail Races have been an integral part of Marine On St Croix's annual calendar since their inception in recent years. Each iteration attracts a diverse group of runners, from seasoned ultrarunners to trail running novices looking for a family-friendly introduction to the sport. The event raises funds and awareness without supporting any specific charity or scholarship but remains deeply rooted within its community as an opportunity for local athletes to come together.
The course for both 50K and 25K races is primarily along William O'Brien State Park's upper section, south side of the park, incorporating Jackson Meadows. The terrain includes gradual ascents and descents with aid stations located every few kilometers throughout the route. Runners will experience two loops on a 25-kilometer stretch for the full 50K race, while participants in the shorter event run just one loop without additional awards or T-shirts but receive an official finisher's print as recognition of their achievement.
For registration, interested runners can visit https://ultrasignup.com/register.aspx?did=131900 to secure a spot until midnight on September 21st for the 50K race and September 22nd for all other distances. Entry fees range from $40 to $75 depending on when registration is completed, with no additional cost for race shirts this year as an option rather than included in entry fees. Bib pickup occurs at William O'Brien State Park Visitor Center before the event where participants can collect their numbers alongside any necessary ID or proof of age if under 18.
The start location for all races is situated conveniently within the park's visitor center lot at 16821 O’Brien Trail North, Marine On St Croix. Age requirements are open to runners aged 13 and older with parental consent required for those under 18 years of age. All participants should arrive early on September 26th prepared for a day in the outdoors.
The OBrien Trail Races at William O'Brien State Park near Marine On St Croix, Minnesota offers both competitive ultrarunners and recreational trail runners an engaging challenge within scenic surroundings during late summer weather conditions. With its family-friendly entry fees and accessible routes that cater to all levels of experience, this race is well worth attending for anyone interested in exploring the beauty of trails through dedicated community events.