Where the GAP crosses "The Line"

Written by Pete Zapadka on .

Bikers on the Great Allegheny Passage who cross the historic Mason-Dixon Line may consider taking a break at the boundary to catch their breath and savor the rich local colonial history.


According to their journal, Charles Mason and Jeremiah Dixon were in this area on Monday, July 13, 1767. They were only beginning their work of that year, having been delayed while negotiations with Native Americans were held to allow the survey party to proceed in marking Pennsylvania's southern border.


In the journal, Charles Mason wrote that day that "at 168 miles 78 chains," they had reached "the Top of Savage Mountain or the great dividing Ridge of the Allegany Mountains." The measurements noted the team's progress as measured from their starting point in present-day northern Delaware.map1


The top of Savage Mountain lies just to the east of the Great Allegheny Passage crossing, and the survey team would have moved through the Great Allegheny Passage area that day.


Just west of the location of the trail's modern-day crossing of the border and three days later, Mason and Dixon were joined by three Onondagas and 11 Mohawks, sent by the Six Nations, the Native Americans who lived in the region. They had come as part of the agreement that allowed Mason and Dixon to proceed westward.


Mason and Dixon first visited this Savage Mountain area on Saturday, June 14, 1766, before the agreement with the Native Americans. Mason wrote in their journal: "Went to the top of Savage Mountain, about 2 miles from the Tents. From hence; to the Summit of the next Ridge called the little Meadow Mountain:


"I judge by appearances to be about 5 or 6 miles: Between this, (Savage or Allegany Mts.) and the said little Meadow Mountain, runs Savage River; which empties into the North Branch of Potowmack: This is the most Westernmost Waters, that runs to the Eastward in these parts. Beyond the Dividing Mountain (Savage), the waters all run to the Westward; The first of Note (which our Line would cross if continued) is the little Yochio Geni (modern-day Casselman River), running into the Monaungahela, which falls into the Ohio or Allegany River at Pitsbourg (about 80 miles West, and 30 or 40 North from hence) called by the French Fort Duquesne."


Mason and Dixon returned to the area on Wednesday, Nov. 18, 1767, to find snow more than a foot deep. More snow fell and a few days later, Mason wrote: "The weather being so bad our Hands would not proceed on their work."


The Mason-Dixon Line was surveyed between Pennsylvania and Maryland, and then Pennsylvania and modern-day West Virginia, from 1764-67. It's somewhat exhilarating to remember the work of Mason and Dixon in the frontier wilderness as we ride along the Great Allegheny Passage in the 21st century.



Marker on the Mason-Dixon Line at Delbrook Lane, several miles east of the GAP crossing (Pete Zapadka/Post-Gazette)


Editor's note: Our Pete Zapadka, the author of this post, is a Mason-Dixon Line guru. He runs the website at and leads the yearly tours for curious strangers and friends. 


Bicyclists of the Point Made! tour will reach the Mason Dixon Mile today, it's Mile 20.5 on the GAP.


Join the conversation:

To report inappropriate comments, abuse and/or repeat offenders, please send an email to and include a link to the article and a copy of the comment. Your report will be reviewed in a timely manner. Thank you.