Rio Del Lago 100 Mile + 50K Endurance Runs

The Jewel of the Sierra Nevada

November 7-8, 2026

Welcome to the 2026 Rio Del Lago Endurance Runs Presented by Altra!

Celebrating 25 Years of the Rio 100 & 5 Years of the Rio 50K!

The celebration is on! The Rio Del Lago Endurance Runs presented by Altra return on November 7, 2026, marking the 25th anniversary of the legendary Rio 100 Mile Endurance Run and the 5th running of the fan-favorite Rio 50K.

Whether this is your first Rio or your twenty-fifth, we’re doing cartwheels to welcome you to this milestone year. Together, we’ll honor a quarter century of endurance, community, and trail magic on one of Northern California’s most iconic courses.

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About the Races

Rio 100 Mile Endurance Run presented by Altra

A true test of grit, determination, and heart. The Rio 100 takes runners on a breathtaking journey from Folsom to Auburn and back, showcasing miles of rolling singletrack, river views, and the rugged beauty of the Sierra foothills.

Rio 50K Endurance Run presented by Altra

Now in its 5th year, the Rio 50K starts alongside the 100 milers at Beal’s Point and follows the scenic early miles of the course. With stunning views along Folsom Lake, Lake Natoma, and the infamous Johnny Cash Trail, it’s the perfect distance for your first ultra or your fastest 50K yet!

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A Milestone Year — A Legendary Experience

As we celebrate 25 years of Rio, expect an unforgettable weekend filled with tradition, camaraderie, and celebration. From world-class race organization and well-stocked aid stations to the warmth of our incredible volunteers, this year’s event will capture everything that makes Rio Del Lago truly special.

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All Entries Include:

• NorCalUltras Goody Swag Bag:
• Commemorative 25th Anniversary Technical Race Shirt:
• Finisher Medallion:
• 100 Mile Finisher Belt Buckle: (sub-30-hour finishers)
• 100 Mile Finisher Athleisure Lightweight Pullover:
• Neversecond Gels on Course:
• Skratch Hydration on Course:
• B-Tag Chip Timing:
• Bob and Brandt's Breakfast Bistro:
• Chef Tim’s “Soup for the Soul”:
• Beer Garden:

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Plan Your Race Weekend

Visit our official website for detailed race information, course maps, and lodging options in our host city of Folsom, California.

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Join the Celebration

Be part of history as we honor 25 years of the Rio 100 and 5 years of the Rio 50K — a milestone weekend filled with tradition, community, and endurance.

25 Years Strong. 25 Years of Grit. 25 Years of Rio.
We can’t wait to celebrate this special year with you on the trails!

– The NorCalUltras Team

Race Registration