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Mason & Dixon Line Page

It all started in the early 18th century. Due to imprecise and confusing land grants, the Penn family (the owners of Pennsylvania) and the Calvert family (who owned Maryland) couldn't agree on the boundaries between the two colonies.


The dispute resulted from the way the “new world” land grants were made.  Charles I gave Lord Calvert, Maryland and, years later, his son Charles II settled his father’s debt with William Penn by giving him Pennsylvania.


But the king’s grants were just wordy descriptions not lines on a map. After years of arguing and a failed attempt by local colonial surveyors to put those lines on a map, these two aristocratic British families asked the Royal Society for help. The society recommended a surveyor and an astronomer, and arranged for a special astronomical tool.


At the time, the most accurate scientific instrument on earth was a 25-foot-tall device at the Royal Observatory known as a zenith sector; essentially, a telescope that points straight up. It was accurate to within one-tenth of one arc second, which is about 3 meters or about 10 feet. So the Royal Society asked the greatest equipment maker of the day, John Bird, to make a six-foot-long version of the Royal Observatory’s zenith sector. The apparatus Bird constructed, just a quarter the size of the observatory’s, was the smallest, most accurate instrument in the world.


In 1763, equipped with Bird’s new instrument, the surveyor and the astronomer left Britain and sailed to Philadelphia to help Penn and Calvert settle their border dispute. 1 With these instruments, Mason & Dixon determined a boundary that is amazingly accurate—within a few feet of surveys done with today’s technology.


The Line, which extends over 230 miles, is commonly regarded as the boundary between the North and the South.  Milestones were placed with an “M” for Maryland carved on the southern face, and a “P” for Pennsylvania on the north.  Every fifth stone had the Calvert coat-of-arms for Maryland on the south and that of William Penn on the north. Drawing the Line took over four years.

Mason and Dixon arrived at the point that crosses the Great Allegheny Passage in July of 1767.

This amazing feat and its impact on our country are celebrated at the Mason and Dixon Line Park on the Great Allegheny Passage, five miles north of Frostburg, four miles south of Deal.

The project was made possible with support from:
Allegheny Trail Alliance
Appalachian Regional Commission
CME Engineering, LP
EverPower Wind Holdings, Inc
Maryland Department of Planning
Mason & Dixon Line Preservation Partnership
National Park Foundation
National Park Service
Pike Electric, LLC
Robertshaw Charitable Foundation
Robindale Energy
Somerset County, PA Tourism Grant Program
Somerset Trust Company

Somerset’s Cook Ancestors and Mason and Dixon
Nicholas Scull II (1687-1761) is considered to have been one of Pennsylvania's greatest surveyors and was surveyor general of Pennsylvania. In 1770 William Scull III, son of Edward and grandson of Nicholas Scull II, produced the first map of the province of Pennsylvania having its southern line based firmly upon the survey that Charles Mason and Jeremiah Dixon had concluded two years earlier.

Somerset’s Cook Family are descended from William Scull. Scull family descendents include the George Scull Cook family of Somerset County

1 Steve Cherry webpage


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