The 11th running of the Stone Mill 50 Mile is completed. Thank you to all the runners and volunteers who supported our race this year. You all did a great job following our COVID plan and keeping everyone safe while enjoying a great day on the trails!
The fifty mile trail run is on the Seneca Greenway and Muddy Branch trails in Montgomery County Md. The course traverses forested, rolling terrain. The course is primarily on single track dirt. There are small stream crossings. Most of the course drains well, but parts can be muddy in wet weather.

Results     2020      Photos

List of all Finishers from the beginning through 2020 (pdf): By NameBy Distance

2021 Course

Click on map to see larger version

See the Course on Strava.

2021 Race Information
Pre-Registration will open in May

*** Please continue to review this page for any additional changes or updates to the race.  We will keep this page updated with the most current information on the race status.

2021 National Championship Race

Due to COVID, we have deferred the championship event to 2021.

2021 Course Preview Training Runs

There are no training runs this year due to social distancing and the pandemic.

Like all of you, we are carefully watching the situation with COVID-19 and monitoring guidance from the CDC and state and local authorities as it pertains to events and large gatherings of people.  At this point in time, we have no reason to cancel the Stone Mill 50 Mile. Every year, our race donates a portion of its proceeds to those local parks and trails who permit us to use their land for this event. As with any event of this nature, the status of Stone Mill 50 will be determined by our ability or inability to obtain permits. Currently, we do not have a permit to hold the 2021 event but anticipate received on closer to to the event date per Maryland rules.
By registering, you are securing your spot to participate, should the race be able to be held. A $0 authorization transaction will be run on your credit card. You will not be charged for the registration until we are able to secure a permit.  Once the race is determined a “go” and your card is charged, all sales are final and there are no refunds.
This year our volunteer opportunities are severely limited due to COVID rules. Our COVID plan is very specific and so the RD will be contacting volunteers directly.

Host Hotel

SpringHill Suites in Gaithersburg is the host hotel with a discounted nightly rate of $99. Call the hotel to make a reservation and ask for the Stone Mill rate or use the link below for the special rate.

Address: 9715 Washingtonian Blvd.  Gaithersburg  Maryland  20878  USA
Phone: 301-987-0900
Website: Book from the Room Block

Alternative Hotel
Sleep Inn: $99 Queen bed or higher for Double.

Address: 2 Research Court, Rockville, MD, 20850,

Parking near start/finish area
Parking at Watkins Mill High School is plentiful with additional parking along Watkins Mill Road.

When – 5AM Start
The Stone Mill 50 Mile run will start at 5:00 AM using a wave start based on previous personal times on Saturday, November 14, 2020. The fastest runners will start first to limit overtaking on the course. The cut off time is officially 13 hours or 7:00 PM and will be STRICTLY ENFORCED due to permit requirements and so we can let our amazing volunteers go home. Intermediate cutoffs are

  • 5:10 to Riffeflord….. 8.4 miles to go
  • 3:10 to Rt 28 ….16.4 miles to go
  • 1:25 to Stone Mill…23 miles to go
  • 12:30 to Pennyfield…..26 miles to go…

Where Start/Finish Watkins Mill High School Parking Lot
The start/finish will be at Watkins Mill High School 10301 Apple Ridge Rd, Gaithersburg, MD 20879

The course will loop around the high school before going onto Watkins Mill Road to the trailhead.

Packet Pickup
Friday, November 12th, outside the host hotel as a drive-through with social distancing in place, 4:30-7:00 PM.

There will be no onsite race day packet pick up due to our COVID plan.

Bag Drops

Stone mill will have 2 drop bag locations on race day. The bags will be collected race morning outside the school/start. There will be 2 separate piles:

  • Mile 24-Pennyfield lock
  • Mile 40-Riffleford road

Please clearly write your last name and bib number on your bag. Our volunteers will attempt to sort them by alphabet. Also please not too large/heavy. Our volunteers are probably not as strong as you are!!

NEW THIS YEAR: The Pennyfield bags will be brought back to the school finish. The Riffleford ones will not be brought back! They become trash after you exit the Riffleford aid station.

Refunds and Bib Exchanges
It’s just not practical to process refunds or bib exchanges. If you decide to withdraw from the race please email Barry and your entry fee will be donated to the State and County parks instead of buying more stuff for the aid stations.

Pacers and Crew
Sorry, no pacers or crew this year. Our county approved COVID plan as well as our permits with the various park services have a strict limit on the number of runners so we can’t allow pacers or crew out on the course for everyone’s safety.