The West Virginia. Cyclopedia
The Fairfax Stone, resting over the headspring of the North Branch of the Potomac River, marked the north-western limit of six-million acre estate of Lord Fairfax of Cameron. Known as the Northern Neck, the vast estate included the Eastern Panhandle of West Virginia and most of the valley of the South Branch of the Potomac. The Fairfax Line, surveyed by Mayo and Savage in 1736, was approved by a survey in 1746 by Peter Jefferson, father of Thomas Jefferson. The stone marks the western limits of the state of Maryland and the corners of Tucker County, Preston County, and Grant County in West Virginia.
Topo map showing location of the Fairfax Stone