Stone Mill 50 Mile Run

Event Overview

Course & Terrain

A 50-mile lollipop from Stedwick Elementary School in Montgomery Village. Runners pass Route 355 (mile 4), Longdraught (9) and Riffle Ford Road (11.7), cross to the Muddy Branch Trail at Quince Orchard (17.4), reach Blockhouse Point Park (23.1) and follow the C&O Canal towpath to the Seneca Stone Mill (27.8). The return runs by Route 28 West (34.3) and Germantown Road (37.2) to Riffle Ford (42) and Route 355 (46).

Key course features to know before comparing this race:

• The Seneca Stone Cutting Mill ruins near mile 28, the quarry mill that supplied the Smithsonian Castle
• The C&O Canal towpath past Violette’s Lock
• The Muddy Branch Trail, with the Quince Orchard station at mile 17.4
• The tunnel crossing at Dufief and Route 28 East, mile 15
• Small stream crossings on forested, rolling single track

Forested, rolling terrain on mostly single-track dirt trail, with small stream crossings. Most of the course drains well, but parts get muddy in wet weather. White flags with the Stone Mill logo and yellow “Stone Mill” ribbons mark the route, with double flags or ribbons before a turn. The towpath is shared with cyclists, hikers and other runners and walkers. The organizer posts a 2026 GPX on CalTopo.

The organizer’s course page links weather history for Dulles Airport and notes that 2022 was a hot year. In 2018 a surprise snowstorm led the county to pull the race permits; an appeal was accepted and the race went ahead on a very muddy course.

Entry & Logistics

Why This Race Matters

Doug Sullivan, Kerry Owens, Michelle Harmon, Joe Clapper and others created Stone Mill in 2010 as an affordable fall race for runners who didn’t want JFK, according to Barry Hauptman, who directed it for 10 years. It is named for the Seneca Stone Cutting Mill, completed in 1868, which supplied the sandstone for the Smithsonian Castle; the ruins sit just before the aid station near mile 28. The first race offered 52- and 56-mile options. Hauptman and Daryl Hultquist took over for 2014, and in December 2023 Hauptman named Ryan Cox as his successor. The start moved from Watkins Mill High School to Stedwick Elementary in 2015, and a loop around Clopper Lake replaced the opening out-and-back in 2016. In 2020 the race went ahead outdoors under county gathering limits, with groups of 20 starting every 5 minutes. Keith Levasseur had finished all 14 editions by 2023 and was fifth in 2025 in 7:55:02. DUV counts 3,462 finishes from 2010 to 2025.

Historical benchmark notes in the directory record (verify current records with the linked official sources):

• Men: Paul Jacobs, 6:41:23, 2020 (fastest time in DUV’s results since 2010; the 2020 race started at Watkins Mill High School)
• Women: Megan McGrath, 7:46:19, 2013 (fastest time in DUV’s results; run before the 2015 start move and the 2016 route change)

Preparing for a Race Like Stone Mill 50 Mile Run

The fixed-distance race guide covers the format as a whole. These guides go deeper:

• Walking strategy for ultramarathons: When and how to walk by terrain, effort and cutoffs.
• Crew and aid-station strategy: Crew tables, aid stops, drop bags and runner preferences.
• Hydration and sodium for ultramarathons: Fluid, sodium, thirst, sweat rate and hyponatremia risk.
• Tapering for ultramarathons: Plan the taper and race week around your own recovery.

Best Fit

• Runners stepping up to a first 50 miler on runnable, mostly single-track trail
• Runners who want aid every 2.4 to 6.5 miles and two drop-bag points
• Returning finishers working toward 5-, 10- or 15-year awards

Planning Notes

• Train for terrain-specific fatigue. Technical trails and mountain courses demand downhill durability, hiking efficiency, and reliable night lighting.
• The directory marks this as having comparatively simpler logistics. That editorial label is not a safety rating; verify cutoffs, terrain, support, crew access, and withdrawal procedures.
• The 13-hour limit (7:00 PM) is strictly enforced because of permit requirements.
• Five intermediate cutoffs apply: Pennyfield by 12:30 PM, Stone Mill by 1:25 PM, Route 28 by 3:10 PM, Riffle Ford by 5:10 PM and Route 355 by 6:40 PM.
• The longest stretch without a full aid station is 7.7 miles, from Route 28 West (34.3) to Riffle Ford (42), with only water at Germantown Road (37.2).
• Mileages differ slightly between the organizer’s pages. The cutoff list counts miles to go, which puts the Stone Mill near mile 27 and Riffle Ford near 41.6; the aid-station page gives 27.8 and 42, and the drop-bag list 40.
• Race-morning packet pickup is very limited, so collect your bib on Friday if you can.

Event FAQs

Related Preparation

• Compare this race in the full 2026 calendar
• Open the Fixed-Distance format guide
• Compare all race formats
• Use the timed-race pace calculator
• Plan checkpoint arrivals and cutoff buffers
• Print a pace band for your goal time
• Estimate race calories and plan fueling
• Build a crew and drop-bag plan
• Build a race-specific gear checklist