Drawing the Mason-Dixon Line
A blog by Emily Pierce, PLS, CFedS
The Mason-Dixon line (choose 2):
a. Is the name of a song made famous by Waylon Jennings
b. Was the border between the North and South during the Civil War
c. Is based on the 40th degree latitude
d. Was surveyed as the border between just two states: Maryland and Pennsylvania
Correct answers:
c. and d.
Incorrect answers:
a. The name of the song is actually Mason-Dixon Lines – where the “Lines” refer to convenient fabrications
b. It’s accepted today that the Mason-Dixon line is the divide between the North and South. But in fact, it’s simply the border between Maryland and Pennsylvania
That border was a big thing in colonial United States. . . Back in those days, the King of England controlled the colonies and granted people and groups tracts of land. The main purpose of these grants was so the Crown could get tax revenue in return.
In 1632, Maryland (governed by the Calvert family) was granted “that part of the Bay of Delaware which Lieth under the Fortieth Degree of North Latitude”. Unfortunately, the fortieth parallel ran right through the middle of Philadelphia, cutting it off from its only harbor. Pennsylvania (governed by the Penn family), didn’t think this was fair, and the case dragged out in English courts for decades. By 1750, a boundary was agreed upon - on paper.
Colonial Map by John Gibson, 1763
Unfortunately, plotting this boundary on the actual land was a challenge that colonists had neither the training nor equipment to do. With more than 4,000 square miles in dispute, a lot was at stake. So in 1763, the Penn and Calvert families hired two English scientists to do the job. Charles Mason and Jeremiah Dixon had studied astronomy and had mastered the complex mathematics of celestial navigation. They were famous as one of the teams mapping the Transit of Venus, which made is easier to figure out the earth’s distance from the sun.
“Stargazer’s Stone” in Embreeville PA.
They arrived in Philadelphia in 1763 as renowned scientists with top-tier equipment and set about the job, which they estimated would take about two years. The first step was to locate the exact starting point, 15 miles due south of Philadelphia. It turned out this spot was right in the middle of a plantation house, so an observation post was built in the front yard. From there they proceeded west following the line of latitude 39 degrees, 43 minutes and 17.6 seconds north.
Limestone survey monuments (called Crown stones) were placed at every mile. One enduring mystery is why these stones were brought all the way from England, since there was plenty of limestone available in the area. Every 11.5 miles, the scientists would line up these posts through their telescopes and make celestial measurements to compensate for error. All distances were measured with a 66 foot Gunter’s chain.
According to Todd Babcock of the Mason and Dixon Line Preservation Partnership, “At the time all Mason and Dixon had in front of them was wilderness. There were some settlements, but west of the Susquehanna River and approaching the Allegheny Mountains there were very few roads. It was all mature forest so they had to come through and cut a vista about 30 feet wide.”
"That required axe-men to cut down the trees, pack mule drivers to get the trees out of the way as well as cows for milk, chain carriers, instrument bearers and tent bearers. It was like a small army moving through the woods.
"They started off with a crew of five, but by the time they got towards the end of the survey the party had grown to about 115.
A crownstone photo courtesy of MDLPP
"When they came into this I think they thought it would take a year or two, but it ended up taking five."
Eventually, 400 five-foot high stone monuments marked the Mason-Dixon line.
Mason-Dixon Line map from the Library of Congress
The map produced by Mason and Dixon is a national treasure and was the first geoedetic survey in the New World.
I know that through my experiences in surveying in northern Wisconsin, I’ve faced some very unfriendly terrain and raw wilderness. But it’s usually on projects that may only take a month or two. I cannot imagine the sheer physical and mental challenge of a project of that magnitude over the course of five years.
After a mentally and physically challenging project, there is always the reward of completion, the satisfaction of the client, and a general sense of success. I wonder if Mason and Dixon realized the lasting significance of their project, and that people would still be talking about it over 250 years later?
Today, surveyors continue to use the best tools to create the most accurate surveys possible. At Berntsen, we’re proud to offer surveyors top-tier markers, monuments, smart targets and other tools for projects large and small.
Couple more interesting Mason-Dixon facts about Mason & Dixon from the BBC:
They were the subject of a 1997 novel by American author Thomas Pynchon
John Bird's fragile Zenith Sector, used for celestial measurements by Mason and Dixon, had to be carried around by the surveyors' team on a mattress
Some historians suggest the word Dixie - a historical nickname for the South - derives from Jeremiah Dixon
Mark Knopfler's 2000 song Sailing to Philadelphia is about the surveyors
Mason has a moon crater named after him
The BBC did a great article on Mason and Dixon: https://www.bbc.com/news/uk-england-40638673
An additional interesting source for more Mason Dixon information is from the New Jersey NJSPLS SurveyCon 2011 “Famous Surveyors —Footsteps to Follow” by Walter G. Robbillard and Kimberly A Buchheit