A canal parallels the Hennepin 100 course in Illinois. Photo Jenny Thorsen

What’s Up in Ultra This Weekend — October 4, 2025

Drew Dinan
Drew Dinan

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October kicks off with 72 North American races on the UltraRunning Magazine race calendar. In this week’s What’s Up in Ultra, we highlight ultramarathons in California, Illinois, Arkansas, Pennsylvania and Alberta, Canada. If you’re a race director and would like your event to be featured in the calendar, register here.

Featured: Cuyamaca 100k (Julian, CA)

Over 250 runners are signed up to run the Cuyamaca 100k this Saturday, just outside of Julian, California. First run in 2012, the race features three distinct loops that take runners on a tour of Southern California’s Cuyamaca Rancho State Park and sections of Anza-Borrego Desert State Park. The first and longest loop is 32.3 miles and traverses the highest point of the course, Cuyamaca Peak, at 6,500 feet. The second loop is 12.6 miles and meanders through the southeast corner of Cuyamaca Rancho State Park. And the final loop is 18.3 miles and features sweeping desert views from sections of the Pacific Crest Trail. Participants have 19 hours to complete all three loops to earn an official finish. Pro tip: stop by the charming town of Julian after the race and treat yourself to a much-deserved slice of apple pie, which the town is famous for. Live tracking here. Read more.

Other West Events:

Pacific

Mountain

Featured: The Hennepin Hundred (Sterling, IL)

The flat and fast Hennepin Hundred (100-mile, 50-mile and 50k races) provides the perfect setting for runners chasing a PR or hoping to earn their first ultramarathon finish. Both the 100-mile and 50-mile courses follow a point-to-point course along the Hennepin Canal State Trail, a 104.5-mile towpath spanning five Illinois counties. The 100-milers will set out from Sterling, IL, and have 30 hours to reach Colona, IL, to earn their Hennepin Hundred buckles. Along the way, they’ll pass by historic locks and bridges, run through quaint towns and picturesque countryside and be supported by over 150 volunteers. Live results here. Read more.

Other Midwest Events:

Featured: Arkansas Traveler (Perryville, AR)

The 34th annual Arkansas Traveler 100 (AT100) kicks off Saturday, October 4, in the Ouachita National Forest. Known for its amazing volunteers, fun atmosphere and passionate running community, the AT100 continues to provide an old-school ultrarunning vibe and promises a genuine “good time running” experience. On course, participants will run a 17-mile loop followed by an 83-mile out-and-back section through the Ouachita Mountains. Along the way, they’ll have to navigate “sneaky hard hills” totaling 12,000 feet of elevation gain and loss, the possibility for a variety of weather conditions (last year’s race saw temperatures in the 90s while 2023 dropped into the 40s) and the likelihood of encountering a variety of slithering and crawling companions on the same trails. Past runners have mentioned encounters with copperheads, timber rattlesnakes, spiders and skunks. There is a 30-hour cutoff, with sub-24-hour finishers receiving a special-colored enamel buckle. Live tracking here. Read more.

Other South Events:

Southwest

Southeast

Featured: Oil Creek 100 Trail Runs (Titusville, PA)

The 17th annual Oil Creek 100 Trail Runs features 100-mile, 100k and 50-mile ultramarathon distances. All events begin at Titusville Middle School in downtown Titusville, PA, before sending runners out on a 50k counterclockwise loop course on the Gerard Hiking Trail in Oil Creek State Park, home to the first commercial oil well in the United States. Each scenic loop (hopefully popping with fall colors on Saturday) features a combination of technical and runnable trails and 5,459 feet of climbs and descents. The 100-milers have 32 hours to complete three loops, and the 100k runners must finish two loops in under 31 hours. The 50k participants have 17 hours to tackle one loop. All finishers receive an Oil Creek 100 buckle that corresponds with their race distance. Read more.

Other Northeast Events:

Featured: Iron Horse Ultra (St. Paul, AB)

The Iron Horse Ultra 100 includes 100-mile, 100k and 60k races set in the Lakeland region in northern Alberta, Canada. All events start and finish at Reunion Station Grounds in St. Paul and take place on a combination of public and private lands on a variety of terrain, including multi-use paths, farmers’ fields, gravel roads, old train beds, forest trails and more. The course is divided into eight distinct legs that 100-milers must finish in under 27 hours. The 100k runners will have 20 hours to complete five of the legs, and 60k entrants have 10 hours to finish three legs. Read more.

Other Events in Canada and Mexico:

Email corys@ultrarunning with questions about adding your event to the UltraRunning Magazine calendar.

Drew Dinan traded the tropics of the Florida Keys for the trails of Bend, OR. Once living the Jimmy Buffett lifestyle, working on fishing boats and owning only a single pair of flip flops, he now has way too many running shoes in his closet and never hears the end of it from his loving wife. He is on a constant quest to find the best happy hours, likes to complain when it’s cold outside, and one day hopes to travel the country writing reviews on chicken wings.

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