Fairfax Stone Historical Monument State Park is a West Virginia
state park commemorating the Fairfax Stone, a surveyor's marker and boundary stone at the source of the North Branch of the Potomac River in West Virginia.
The original stone was placed on October 23, 1746 to settle a boundary dispute between Thomas Fairfax, 6th Lord Fairfax of Cameron and the English Privy Council concerning the Northern Neck of Virginia. It determined the proprietorship and boundaries of a large tract of mostly unsurveyed land in the English colonies of Maryland and Virginia. Fairfax Stone Historical Monument, part of a four-acre West Virginia state park, is six miles north of Thomas, West Virginia. There are no facilities.