The Mason-Dixon Line, which settled a border dispute dating back to the founding of Philadelphia, is the southern boundary of Pennsylvania. Originally surveyed by Englishmen Charles Mason (1728-86) and Jeremiah Dixon (1733-79), the line separates Pennsylvania from Maryland and West Virginia along the 39º43ˊ N. parallel and bounds Delaware along an arc that extends from Maryland to the Delaware River. During the nineteenth century the line became a symbolic boundary between the southern and northern United States.