Stone Mill 50 Mile Run

Gaithersburg, United States • 8 Nov 2025

The MCRRC Stone Mill 50 Mile Run is a 50-mile trail ultramarathon in Montgomery Village, Maryland, organized by MCRRC. The course uses forested, rolling terrain along the Seneca Greenway and Muddy Branch trails in Montgomery County, primarily on single-track dirt trails with small stream crossings. Runners should expect well-drained sections but muddy conditions after rain.

Finishing takes place at Stedwick Elementary School in Montgomery Village. The race honors long-time finishers with 5-, 10-, and 15-year milestones, and offers volunteer opportunities and sponsor support. The event emphasizes trail stewardship and features aid stations, spectator tips, and a strong local running club community. Visit the organization's website for the most recent information.

Race information

UTMB 50K
50 mi
50 Mile
Visit the organization's website for the most recent information.
Trail runs nearby

St. Anselm's Family 5k is a family-friendly fundraising race in Washington, DC, held at 4501 South Dakota Ave NE. The event covers a 5k distance on a double-loop trail course, suitable for runners and walkers alike.It benefits a memorial scholarship fund at St. Anselm's Abbey School, supporting stud..

River's Edge Endurance Challenge is a nonprofit running event held at Brunswick Middle School, Maryland. The lineup includes a 5K (3.1 miles), a 3-Hour Endurance Race, and a 6-Hour Endurance Challenge. The largely trail-based course runs on the River's Edge Trail System, with about a mile on school..

The Fall Harvest 5k is a scenic trail race held at Claude Moore Park in Sterling, Virginia. Set amidst the vibrant colors of autumn, the course features forest paths and leaf-covered trails, offering a picturesque experience for both runners and walkers. This event is part of the Run Your PRCS Parks..

MoCo Dems 5K Fall FunRun is a 5K run/walk at Agricultural History Farm Park in Derwood, MD. Organized by the Montgomery County District 15 Democratic Caucus, it offers a 5K for adults, a Youth 5K, and a free option for youth 10 and under. The course is a natural trail through the park, with water st..

The Rick O'Donnell Memorial 5 Mile Trail Run & Ultra Challenge takes place at Milkhouse Brewery at Stillpoint Farm in Mount Airy, Maryland. In its 13th year, the event offers three ways to test endurance: a single 5-mile trail loop, a 4-hour challenge, and an 8-hour ultra challenge. The hilly course..

The Westover 5k & 10k takes place on October 18, 2025, at Bon Air Gardens in Arlington, VA. Distances offered: 5k 10k The event awards points toward the Year-Long 5k, 10k, and Back of the Pack Series, and toward the Fall Series. A virtual run option is available. Walkers and strollers are wel..