Mary Saner - March 2007
Finding the Invisible Mason-Dixon Line
When Charles Mason and Jeremiah Dixon came from England to the Eastern Shore in the early 1760’s, they were hired to settle one of the most storied land disputes in colonial history. It was one lasting almost a hundred years between the wealthy families of William Penn and George Calvert.
England had provided both families with huge land grants, giving the Penns rights to Pennsylvania and its three lower counties (present day Delaware), and the Calverts control of Maryland. But the description of boundaries in the grants differed causing much confusion and animosity in the two colonies. A Calvert or Penn sometimes strayed onto land claimed by the other, and more than once it resulted in bloodshed.
After years of feuding and unsuccessful efforts by local surveyors to chart the boundaries, the Penn and Calvert families appealed to the High Court of England for a solution. Enter Charles Mason and Jeremiah Dixon.
Mason was an expert surveyor and astronomer. While studying stars and the moon at The Royal Society in Greenwich, England, he was commissioned to go to Sumatra and observe a rare transit of Venus (Venus seen crossing the sun). Jeremiah Dixon, a surveyor and less experienced astronomer, was selected to go with him. Their observation of the transit ended up taking place in Cape Town, South Africa and gained the pair some notoriety. Such was the beginning of a famous friendship and team.
Both men were considered excellent recruits for the job in America, and both yearned for a new adventure. Following the High Court’s decision on some technical aspects of the boundary, Mason and Dixon agreed to meet in England with Thomas Penn and Frederick Calvert, heirs to their family’s land. Hearing details of the dispute, the Englishmen signed a contract with Penn and Calvert agreeing to go to the colonies and help draw the boundary lines in question. They were promised a fee of at least 600 pounds each for their work.
On November 15, 1763, ten weeks after setting sail from England, the two surveyors arrived in busy, prosperous Philadelphia. They would spend the winter there meeting with local leaders and surveyors, and finalizing a plan.
Come spring, they set off south on horseback towards the Delmarva Peninsula. It was agreed that the survey would begin at the transpeninsular “Middle Point” which is halfway between Fenwick Island and the Chesapeake Bay, for local surveyors had succeeded in charting the southern border of Pennsylvania’s three lower counties (Delaware).
The Middle Point is the present day southwest corner of Delaware. Here, Mason and Dixon’s team gathered; it was made up of 39 men including surveyors, ax men to clear the woods, laborers for laying down chains as markers, and cooks. The area soon resembled a small village with horses, wagons, tents, and supplies of food and medicine amassed for the journey.
In late June 1764, carrying hand-held instruments including a compass and Hadley’s quadrant, Mason, Dixon and their team set off walking north from the Middle Point (a small shelter and 3 stones now mark the place). Their goal was to precisely measure latitude and longitude from the stars, boundary settlement terms, and landmarks.
It was rainy and muggy as they began crossing Delmarva’s fields and swamps. Wagons kept getting stuck in mud, having to be dragged out. At one point, progress completely stopped for the swamps were too deep to get through.
Marking their slow progress, the men lay down “Gunter’s Chains” along the charted line. Invented by English mathematician, Edmund Gunter, the 22 yard chains which were divided into 100 links of solid bars, were commonly used by surveyors for measurement.
At each mile, Mason and Dixon also placed a marker, for later, a large engraved stone brought from England would be set down at the exact spot. The mile stones showed a P and M carved on opposite sides. Every 5th mile, a larger “Crownstone” weighing as much as 800 pounds was used. Crownstones had the Penn coat of arms on one side, the Calvert coat on the other.
Due to wetness and frequent hot spells, the expedition took longer than planned, though work went on night and day. The astronomer, Mason, did much of his work at night, for observations of stars guaranteed they were following a straight line.
Reportedly, the team crossed the Choptank River on July 25, and two days later celebrated Dixon’s 31st birthday.
It would take nearly four months more for Mason and Dixon to complete surveying the north/south boundary. Their line - absolutely straight and stretching 83 miles - stands today as the boundary between Maryland and Delaware.
Thanks to the restoration efforts of the Mason-Dixon Line Preservation Partnership, founded in 1990, most of the marker stones are still in tact, and form the invisible Mason-Dixon Line. While many of the stones are now hidden in woods or beside over-grown fields, some can be seen from the road. In the center of the town of Marydel is an engraved crownstone with the Penn coat of arms still visible. While weathered, it stands upright.
Mason and Dixon would continue on to chart the east-west Maryland/Pennsylvania border, and leave markers for stones there, as well. They finished the whole Line in October 1767 - more than four years after they began. While their Line would become famous during the Missouri Compromise of 1820 and the ensuing Civil War, for dividing North from South, freedom from slavery, its original purpose remains largely the untold tale.