Side Quest: Briar Patch hunt for Lancaster County’s only Mason-Dixon Line Crownstone

Lancaster County has five Mason-Dixon line markers along her southern border. I recently posted about an easy to get to one at the intersection of Grubbs Corner Road and Pilottown Road. Another is located inside Lancaster Conservancy’s Rock Springs Nature Preserve. I attempted to find it once before but was defeated by an incredibly thick briar patch. Last weekend I tried again. This time wearing thicker pants and leather work gloves. Here’s what I found.

A Brief History

To settle a Colonial America border dispute involving Maryland and Pennsylvania, surveyors Charles Mason and Jeremiah Dixon worked from 1763 to 1767 to delineate the borders of Maryland, Delaware, and Pennsylvania. The dispute had originated decades earlier from somewhat confusing proprietary grants by King Charles I to Lord Baltimore (Maryland) and King Charles II William Penn (Pennsylvania).

In 1730 the disagreement over the border’s location erupted into a series of violent incidents prompted by property rights and law enforcement disputes. It escalated through the first half of the decade, culminating in the deployment of military forces by Maryland in 1736 and by Pennsylvania in 1737. The armed phase of the conflict ended in May 1738 with the intervention of King George II, who compelled the negotiation of a cease-fire. The battle became known as Cresap’s War.

A final settlement was not achieved until 1767, when the Mason–Dixon line was recognized as the permanent boundary between the two colonies. In 1784, surveyors David Rittenhouse and Andrew Ellicott and their crew completed the Mason–Dixon line survey to the southwest corner of Pennsylvania. Other surveyors continued west to the Ohio River. The Mason–Dixon line was resurveyed in 1849, 1900, and the 1960s.

The line was marked by stones every mile and a larger “crownstone” every fifth mile, using materials shipped from England. The smaller every-mile stone pillars have an “M” on the Maryland side, and the Delaware and Pennsylvania sides say “P.” Here’s an image of one found at the intersection of Grubbs Corner Road and Pilottown Road.

On the other hand, the more prominent crownstones boundary monument included two coats of arms. These markers are ornamented with family coats of arms facing the state they represent. On the Pennsylvania side is William Penn’s coat of arms, while the opposite shows the coat of arms of Maryland’s founding Calvert family.

While some of the original stones are missing or buried today, many are still visible. Others have been replaced with new markers after time and the elements have worn the originals away to almost nothing.

Searching for the Marker

As I mentioned above, Lancaster County has five Mason-Dixon line markers. However, only two are publically accessible. One is at the intersection of Grubbs Corner Road and Pilottown Road, and the other is inside Lancaster Conservancy’s Rock Springs Nature Preserve. Sharp thorns had thwarted my first visit to the nature preserve.

Rock Springs Nature Preserve. Image courtesy of Lancaster Conservancy.

Clad in thicker pants and leather work gloves, I recently tried again. The trail was worse than I remembered—a boggy mess with dense briars. My son and I felt like Frodo and Sam picking our way through Emyn Muil and the Dead Marshes on our way to Mordor.

After much trial and error, we eventually found a deer path that led us to the marker. To my surprise, it was a crownstone!

I made a LiDAR scan of the crownstone if you want to interact virtually with the object without having to deal with all the thorns.


Where to Find the Marker

You can find the crownstone on the border between Lancaster Conservancy’s Rock Springs Nature Preserve and Old Dominion Electric Cooperative’s Wildcat Point Generation Facility in Maryland. Here are the GPS coordinates for the crownstone: 39.721333, -76.166778.


If you are a glutton for punishment, here are some additional tips for locating the crownstone. Instead of accessing the trailhead closest to the parking lot, continue walking southeast on the road. There is another trail access point further down. It has only a few briars. Here are the GPS coordinates: 39.724210, -76.161590 for the trailhead. The spot is marked with a black X on the map immediately below.

Continue on the trail to the area with the yellow circle. Here you can follow a deer trail until you eventually reach the marker. You will need to hop a small stream or two along the way.

Rock Springs Nature Preserve trail. Map courtesy of AllTrails.

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William Penn Coat of Arms visible from the Pennsylvania side.


You can own beautiful reproduction maps of Fulton Township, where this Mason-Dixon marker is located.

Learn More

Sehner-Ellicott-von Hess House: Home to the surveyor who helped define America

Today, 123 North Prince Street houses the Historic Preservation Trust of Lancaster County, but in the early 1800s, America’s best and brightest mathematician and surveyor, Andrew Ellicott, lived here. Click the link to learn more.

Side Quest: Artifact Hunt for a Mason-Dixon Line Stone Marker

Pennsylvania side of the Mason-Dixon line

This side quest has you doing an artifact hunt for one of the Mason-Dixon line stone markers. Click here to read more.

Armchair Explorer: Make your reservation today for the Pequehanna Inn – Pennsylvania’s Crown Jewel answer to Lake Placid

In an alternate universe, a five-story, 384-room luxury hotel sits high on a hill above the town of Pequea with a commanding view of the Susquehanna River. Click here to learn the uncanny history of the failed Pequehanna Inn.



3 thoughts on “Side Quest: Briar Patch hunt for Lancaster County’s only Mason-Dixon Line Crownstone

  1. You should correct your fact about which king(s) gave the charters. The charter to Maryland was by King Charles I (the first). The one to Penn was by Charles II (the second) quite a few years later.

  2. Went to try and locate this today. Was well prepared with regards to gear and clothing.
    Aside from a lot of ticks and thorns, both high and low, two hours of searching lead to a lot of dead ends and no stone. I used a compass on my phone and was at the coordinates of the circle. I tried using GPS for the crown stone coordinates but it took me on the Maryland side either behind or on the electric plant property. I used it on walk mode while in the thick of things and it told me to go on the road. I figured since this was posted in January, the directions would have been pretty good but the briar growth was too bad. Saw a lot of deer 💩 but no deer. I did see a fair amount of markers and followed them as much as I could but it led to a patch to thick with thorns. I felt like this was the way but without a suit of armor, I wasn’t tackling the briars. I do plan to try again so any other tips are appreciated. Also didn’t see any water at all.

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