Near Newark in New Castle County, Delaware — The American Northeast (Mid-Atlantic)
The Post Mark'd West
A significant detail in the Mason and Dixon Survey
Photographed by Pete Skillman, March 25, 2024
1. The Post Mark'd West Marker
After decades of dispute over property boundaries, the proprietors of the provinces of Maryland and Pennsylvania hired English astronomers and surveyors Charles Mason and Jeremiah Dixon to "run out, settle, and define" the boundaries between the provinces.
In 1763, Mason and Dixon were charged with running an east-west line 15 miles south of the southernmost part of Philadelphia. They surveyed from the Stargazers Stone in Embreeville, Pennsylvania, 15 miles south to the latitude 39° 43' 18.2" in a field on the farm of Alexander Bryan.
There, on June 12, 1764, they erected a 4" x 4" oak post with the word "West" on it. Mason referred to this marker in his journal as "the post mark'd west." This oak post lay on the latitude of the Maryland and Pennsylvania boundary; not on the east-west boundary.
Eventually the post was lost. In 1952, historian and Mason-Dixon hobbyist William T. Mahoney found the site on the property of Halleck DuPont and marked it with a small post. In 1953, DuPont put up this stone monument to mark the site.
Learn more about the history and importance of the Mason-Dixon line at the Chambers
this page online
(Captions):
Map illustrating the surveys of the Pennsylvania, Maryland and Delaware boundaries. Excerpted from the Journal of Charles Mason and Jeremiah Dixon.
Mason and Dixon at the Stargazer's Stone, by Brian F. Tucker. Courtesy of The American Surveyor
The Gunter chain, a 17th century land survey tool, was used by Mason and Dixon during the establishment of the boundaries of Pennsylvania and Maryland. National Museum of American History, Smithsonian Institution
Erected 2017 by Delaware State Parks.
Topics. This historical marker is listed in these topic lists: Colonial Era • Landmarks • Political Subdivisions. A significant historical date for this entry is June 12, 1764.
Location. 39° 43.344′ N, 75° 43.939′ W. Marker is near Newark, Delaware, in New Castle County. It can be reached from Bryan's Field. Touch for map. Marker is at or near this postal address: Bryan's Fld, Newark DE 19711, United States of America. Touch for directions.
Regionally, this marker is in Greater Wilmington and in Greater Philadelphia. It is also in the American Mid-Atlantic and on the Delmarva Peninsula. Globally,
Photographed by Pete Skillman, March 25, 2024
2. The Post Mark'd West Marker wide view
Other nearby markers. At least 8 other markers are within 2 miles of this marker, measured as the crow flies: Site of Post Mark'd West (here, next to this marker); Pioneer of Preservation (approx. 0.4 miles away); Ebenezer United Methodist Church (approx. 1.1 miles away); Original Site of the White Clay Creek Presbyterian Church (approx. 1½ miles away); Eastburn-Jeanes Mining Complex (approx. 1.6 miles away); The Judge Morris Estate (approx. 1.7 miles away); a different marker also named Judge Morris Estate (approx. 1.8 miles away); Dorothy P. Miller: Champion of Preservation (approx. 1.9 miles away). Touch for a list and map of all markers in Newark.
Another marker is no longer nearby. The Judge Morris Estate (was approx. 1.8 miles away but has been replaced with another marker now near it).
Credits. This page was last revised on April 1, 2026. It was originally submitted on March 25, 2024, by Pete Skillman of Townsend, Delaware. This page has been viewed 1,091 times since then and 93 times this year. Photos: 1, 2. submitted on March 25, 2024, by Pete Skillman of Townsend, Delaware. • Bill Pfingsten was the editor who published this page.
