Born from the success of Mammoth Trail Fest, theMAMMOTH is the latest big vision from race founder Tim Tollefson and race director Hilary Yang—an event that pushes limits while staying rooted in community and connection.

Tim, a professional ultrarunner turned race organizer, has already proven his ability to create unforgettable trail experiences. With Mammoth Trail Fest quickly becoming one of the most celebrated trail races in North America, he now brings that same energy and passion to theMAMMOTH, building a space where runners of all levels can chase bold goals against the backdrop of the Eastern Sierra.

Joining him is Hilary, whose deep background in ultrarunning media and creative direction uniquely shapes the identity of theMAMMOTH. As co-founder of the Women’s Trail Running Fund, she’s been a driving force in making trail and ultra spaces more inclusive, and she brings that commitment into every detail of this race.

Together, Tim and Hilary are crafting an event that’s not just about distance, but about discovery—of self, of community, and of the rugged beauty of the Sierra.

theMAMMOTH isn’t just a race. It’s an experience built to inspire.