The Mason-Dixon Line, the iconic dividing line between North and South, is an invisible line running across the backyard of many Delaware, Maryland and Pennsylvania residents.
Charles Mason and Jeremiah Dixon’s milestone markers still dot the Maryland-Delaware-Pennsylvania border more than 240 years after they completed their survey.
Take Delaware portion: jutting out of the dirt on rural roadsides, highway medians and private property, the 81 original oolitic-limestone markers and six replacements run like a dotted line from near Delmar in lower Delaware north to Newark in the state’s uppermost county .
This is the eastern-most leg of the legendary line immortalized in songs and movies and “Looney Tunes” cartoons, and the only chunk that is mainly vertical.
Rewind to 1763, when Mason and Dixon docked in Philadelphia, two English astronomer-mathematicians who came highly recommended by the director of the Royal Observatory at Greenwich. Their task: Discern the 233-mile border between William Penn’s land and Cecilius Calvert’s.
Geodetics, the present-day science that deals with measuring the Earth, was practiced mostly by ship’s captains and astronomers then. Measurements varied so wildly that some ships’ captains believed Philadelphia was actually part of Maryland. No one had ever measured a boundary so long that the Earth’s curvature would come into play.
“Today, it’s a no-brainer,” says Brian Cannon, historic interpreter at the New Castle Courthouse Museum in New Castle, De. “You plug into a computer and it tells you just what to do, but back then, it required making some temporary lines, measuring a line on the ground, and then going back and adjusting that line based on what you know. It was a very math-heavy problem.”
Mason and Dixon’s job was to settle a three-generation-long boundary dispute between the Penns and the Calverts. Both families had been deeded land by British kings, but the deeds overlapped. The landlords had trouble collecting taxes from colonists because it was unclear who owned what. One colonist poked more than a dozen rifles through his log-cabin walls to protect his property. Ironically, less than eight years after the survey was finished, the American Revolution would make it inconsequential.
Their line became shorthand for slave states and free states when it was mentioned on the floor of the U.S. Congress in raucous debates over the Missouri Compromise of 1820.
It became the invisible border between Southern culture and Yankee culture.
The differences weren’t just in the back of people’s minds; the train tracks above the line were a wider gauge than those below the line until 1886.
“It’s unlike any other boundary in the world,” says William E. Ecenbarger, who walked as much of the line as he could reach to write “Walkin’ the Line: A Journey From Past to Present Along the Mason-Dixon Line.”
“One is it’s a very famous geographic line with many, many historic significances, and the other is it’s a line that played a very symbolic role in the Civil Rights movement, even into the 1960s,” Ecenbarger says.
Mason and Dixon started their work at a Colonial survey marker called Middle Point in the extreme southwestern corner of present-day Delaware. Their marker is still located along Del. 54 in Sussex County, De., just five miles west of Delmar. If you’re considering a road trip, look for four stones in a brick enclosure.
As they surveyed north and west, the duo measured distances with wrought-iron chains and surveyor’s instruments such as the transit — a combination compass-telescope that allowed them to take vertical and horizontal measurements. They used trigonometry to compute distances, heights and angles.
During the Delaware leg of the survey, they could have been spotted at the New Castle Courthouse or at St. Patrick’s Tavern in Newark, on the site of the present-day Deer Park Tavern. Most colonists wouldn’t single them out, though, because their names didn’t become well known until decades after their deaths.
Mason and Dixon trudged through flooded fields and cold creeks, and faced snakes and wild animals on their 233-mile trek with a team that included Native American guides, tent carriers, chain carriers and ax men, who cut trees to open up 24-foot to 27-foot paths called “vistas” so telescope sightings could be made.
Present-day Delaware is east of the Mason-Dixon Line, but it was once part of William Penn’s land, called the lower three counties along the Delaware. The present-day western border of the state divided Penn’s land and Calvert’s “Maryland.”
Mason and Dixon’s line is still accepted by the U.S. Geodetic Survey, and it became the model for British and American boundary makers. But the mathematicians had no idea their names would be commemorated for centuries to come when they boarded the Halifax Packet for the voyage back to England.
State officials and history buffs are combining efforts to protect the 81 original markers that remain along Delaware’s western border. One marker reportedly was removed and placed in a fireplace mantle. Another was uprooted for display at the 1904 St. Louis World’s Fair and went missing until the Marydel Lion’s Club found it and returned it to the boundary in 1964.
How to spot a line marker
Mason and Dixon first planted wood markers every mile as they surveyed. Then they replaced those with stone markers inscribed with “M” for Maryland on the Maryland sides and “P” for Pennsylvania on the opposite sides. Every fifth mile was marked instead with a “crownstone” — a taller, more ornate marker with the Calvert coat of arms on one side and the Penn coat on the other. Mile-markers were 12 inches square and 3 1/2 feet high. Crownstones stood 5 feet high.
Is there a marker that’s easy to find?
While many markers are on private property, the marker on the Delaware-Maryland line in Marydel is easy to find. The centuries-old marker, surrounded by a very short barrier, is directly across the street from the PNC Bank at 211 Railroad Ave. Marge Messner, who moved to town in 1976, says families and school classes often visit to take pictures in front of the monument. Messner says the really ardent enthusiasts sometimes jump the barrier to pose with the stone. “It’s a piece of history,” she says.
For a marker road trip, drive due south from Reliance, De., on State Line Road and watch your odometer. Exactly one mile south of Reliance, you’ll see a manhole cover in the middle of the road, says Cannon. If you’re wondering if there are underground utilities on rural farmland, there aren’t. Underneath the closed manhole cover is a Mason-Dixon mile marker. And, if you drive exactly one more mile south, Cannon says you’ll see an ornate crownstone. State Line Road bears right into Maryland just before the stone, he says, but if you drive straight ahead onto the farm road that extends straight in front of your car, you’ll see the original stone with the Penn and Calvert coats-of-arms just up the embankment on your left.
Charles Mason and Jeremiah Dixon sailed from New York harbor on Sept. 11, 1768 — exactly 233 years before the attack on the World Trade Center. They boarded the Halifax Packet for Falmouth, England. Dixon never returned to America, and the two never worked together again.
The remaining Mason-Dixon markers are a unique treasure for Delaware, Maryland and Pennsylvania. There is no other boundary in the world marked with foreign stones, says William Schenck, a scientist with the Delaware Geological Survey.
Many of the original limestone markers have been replaced, but some originals can still be found. A few originals have been stolen, eroded by swamp water and chipped by souvenir-seekers. One presumed Delawarean tried to change a marking on a stone from a “P” to a “D.”