West Virginia-Pennsylvania Sinclair Cornerstone

The West Virginia-Pennsylvania Sinclair Cornerstone is a historic marker located along the border of Marshall and Wetzel counties. Located on a remote, wooded hillside near the boundary between West Virginia and Pennsylvania, it identifies the point at which West Virginia's northern panhandle begins, and serves as the western terminus of the Mason–Dixon Line and the southern end of the Ellicott Line, which forms Pennsylvania's western boundary.

Source: Wikipedia — West Virginia-Pennsylvania Sinclair Cornerstone (CC BY-SA 4.0)