IRONSTONE 100K: Legs of Iron. Resolve Like a Stone.

Ironstone 100K
Legs of Iron. Resolve like a Stone.

Ironstone 100K: A Test of Endurance on the Wildest Trails of the Alleghenies 

Runners with legs of iron and resolve like stone will gather in Central Pennsylvania on July 12-13, 2025, to take on the forth annual Ironstone 100K Ultramarathon. This savage and grueling 100-kilometer (62-mile) point-to-point race weaves through some of the most challenging and scenic terrain in the Alleghenies, spanning Blair, Huntingdon, and Centre counties in Southern Pennsylvania.   

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A Brutal, Beautiful Challenge
The Ironstone 100K is known for its rugged, technical terrain, drawing comparisons to some of the toughest ultramarathons in the region, such as the Eastern States 100, Black Forest 100K, and Worlds End Ultramarathon. With no pacers, limited aid stations, and a 2 p.m. start, runners must rely on their own endurance and strategy to complete the course within the 23-hour time limit.  

The journey begins at Canoe Creek State Park in Blair County, where runners enjoy a fast, flat start along the Lower Trail (rhyming with "flower"), following the Frankstown Branch of the Juniata River. However, the real test begins shortly after crossing the Little Juniata River, where the course transitions into some of the most demanding terrain in Pennsylvania.  

Among the race’s defining features is an extended nighttime stretch along the Mid State Trail, running atop the Tussey Mountain ridgeline —one of the longest named ridges in the Appalachians. The trail’s rocky, fractured surface demands focus and resilience. Other highlights include:  

• The old-growth pines of Alan Seeger Natural Area

• The craggy ledges of Indian Wells 

• A breathtaking sunset at Spruce Knob and Colerain and sunrise west of Bear Meadows

• The final push along the Standing Stone Trail before finishing at Greenwood Furnace State Park  

A Growing Tribe of Runners
The Ironstone 100K continues to attract runners from across the country and beyond. In 2024, participants represented 15 states from coast to coast, with some runners traveling from as far as Australia, Yukon Territories, and the Philippines.  

Race Director Benjamin Mazur, who also serves as Vice President of the Eastern States Trail-Endurance Alliance, takes pride in the race’s growing reputation:  

“This race, with its challenge and heritage, is introduced to a new set of runners each year, and that never gets old,” Mazur said.  

The Ironstone 100K is not an entry-level race. All participants must have completed at least one official 50K trail race within the advertised cutoff time before registering. Exceptions may be made for similarly difficult races, but participants must contact the race directors for approval.  

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A Race Like No Other 
With summer temperatures usually climb into the 90s but even in more moderate conditions, the Ironstone demands everything from those who attempt it.  

Finishers will be rewarded not just with a custom metal finisher’s award and the iconic Ironstone flannel shirt, but also with the satisfaction of having conquered one of the toughest ultramarathons in the region. The post-race celebration at Greenwood Furnace State Park will feature breakfast and/or lunch on us, beer from Levity Brewing, and coffee from Buzzsaw Coffee.  

The Ironstone 100K is made possible through the support of the Pennsylvania Department of Conservation and Natural Resources, the Mid State Trail Association, and the Standing Stone Trail Club, among other organizations.  

For those who believe they have what it takes—legs of iron and resolve like stone—this race offers the ultimate test. Will you take on the challenge?