Mason-Dixon Longest Day Challenge

The Mason-Dixon Trail

Longest Day 100K Challenge

A low-key Trail Dawgs invitational running celebration and picnic

Saturday, June 19, 2021

Start: Rock Run Mill, Susquehanna State Park, Maryland

Sunrise: 5:38ish am

Finish: Shanks Mare Store, Long Level, Pennsylvania

Sunset: 8:38ish pm

2020 Reigning Fastest Finisher: Eddie Pantoja 12:44

Men's Fastest Finish Ever: James Weaver 10:30 (2019)

Women's Fastest Finish Ever: Jackie Palmer 12:01 (2014)

Fastest Unsupported "Dixon" Finish Ever: James Weaver 10:30 (2019)

Oldest "Challenge" Finisher Ever: Henry Peck, 57 (2014)

Youngest "Challenge" Finisher Ever: Jake Landon, 19 (2019)

How will you meet the challenge in 2021?

Hoping for a normal, covid-free, disorganized non-event


Visit MDLD 100K on Facebook!

Name your challenge!

Can you run 100 of the gnarliest kilometers of the Mason-Dixon Trail in between sunrise and sunset on the Saturday nearest the longest day of the year? We'll write your name on this website if you do.

A. The Jeremiah Dixon 5000 Chain Traverse: Run self supported without a crew or pacers. Carry your own provisions and use food, drink, and ice at our picnic grounds and water drops, but no other external assistance. This is for the hardcore. Ole Jerry Dixon had to drag miles of chain (80 links per mile) along the PA-MD border. Be like him and drag your own britches the 60+ miles without much help.

B. The Charles Mason Celestial Passage: Use whatever crew or pacers you like. Chuck Mason needed a lot of help with his astronomical equipment while surveying the border. You want help, too? That's OK. It's tough even with lots of help!

For either challenge, runners can choose:

  • The Original Sunrise-to-Sunset option (05:38 to 20:38 - total time 15:00)
  • Civil twilight option: (approx 05:05 to 21:12- total time: 16:06)
  • Nautical twilight option: (approx 4:24 to 21:54 - total time: 17:29)
  • Astronomical twilight (approx 3:36 to 22:42 - total time: 19:04)

The Picnic: Your Trail Dawg friends will be hanging out with drinks and munchies at Cold Cabin Park, Lock 12 Interpretive Area, and Otter Creek Campground, cheering on those brave enough to attempt the challenge!

2021 Picnic Directors: Usually Pete McLaughlin (, Hunt Bartine (, Rob and Cathy Bartholomew ( with special York County hospitality by Roxanne and Dave Strine.

How to Enter: This run is a Trail Dawg running party. It is a personal challenge and celebration of trail running for our friends, not a race. It is a free individual effort, and not to be considered an organized, sponsored or affiliated endeavor; no applications, fees, releases, etc. And, as this is not a real event, remember that your Trail Dawg pals are just there to cheer on individual runners brave enough to try to do this, and to record your name for posterity on our web page if you succeed. Nothing more. You're responsible for your own foolish decision to try to run this route. Don't expect much more from it other than self-fulfillment. You would have more fun picnicking with us than trying to run 62 miles on a hot day.

If you want to get on the 100K challenge list, please provide documentation of completion of a 50 mile or longer race in the last two years at a reasonable speed -- or to convince us you know this trail really well. This party always has less than 25 invited. First dibs were given to previous participants so recognized openings for "The Challenge" are very limited.

That said, email one of the Picnic Directors if interested in an invite.

Email group: When you enter MDLD, we'll add you to the email group list so you can chat with other runners about logistics and trail lore.

Aid and Run Support: "None" is what we always promise. We're busy having a picnic and you want us to help you? OK, actually we'll be there to cheer you on and hope you'll meet us at our picnic stops to enjoy the food and cold drinks! Some of us think it is fun to make fun of fools trying to run 100K on a hot day while we picnic. Feel free to share your favorite goodies. We'll also stash water at several places along the trail so we can be sure none of our friends get dangerously thirsty. Please see the Water Drops page for locations. However, please plan to be self-sufficient and carry essential supplies with you.

Transportation: This a point-to-point run. You're responsible for coordinating your own transportation. However, it's been easy most previous years for most runners to coordinate car drops with other runners. The MDLD email group is a good way to communicate with fellow runners about this. Email us and we can tell you how to sign up for this email group.

Trail Markings: Mason Dixon Blue Blazes and good sense of direction. Interested runners should purchase a set of the beautiful updated maps published by the Mason-Dixon Trail System and carry them. This run's challenge includes the not-always-easy task of following the course blazes and remaining on the Mason Dixon Trail.

View some Mason-Dixon Trail maps here

The standard Trail Dawgs Fat-Ass disclaimer applies: No Fee, No Frills, No Wimps, No Whining!

Site maintained by Pete McLaughlin (, Newark, DE. The information on these pages is, like many inspiring running books (Ultramarathon Man, Born to Run), partly accurate, partly fictional, and for entertainment purposes only; neither I nor the TrailDawgs are responsible for any inaccuracies, misinformation, exaggerations, or outright lies included herein. Thanks to Pawl Melzer for many of the original materials used for these web pages.