The Mission On November 15th, 1763, Charles Mason and Jeremiah Dixon arrived in Philadelphia with instructions from the Royal Society. Their errand in America was expected to provide a solution for disputes on boundary lines which had been an issue for 80 years and more between the aristocratic family of the Penns and the noble family of the Calverts, Lords Baltimore.
The grant to Baltimore on June 20, 1632, described the territory running from Cape Hinlopen (now Fenwick Island in the Atlantic Ocean), limited to the north by the 40th parallel of Latitude and running from the Delaware River and Bay Westward to the headwaters of the Potomac River.
George Talbot, of Susquahanna Manor, a kinsman of Lord Baltimore, and a dashing and notorious adventurer along the upper reaches of the Chesapeake, claimed a territory along the ‘Talbot Line’, a rude boundary marked only by blazed trees, in 1683.
After the conference of 1685 determined that the provinces on the Delaware belonged to William Penn because Lord Baltimore’s patent was for “uncultivated land” whereas the land in dispute was inhabited by Christians before the date of the Maryland patent. The northern boundary line was far from settled although the committee is said to have favored the fortieth degree of latitude.
William Penn’s action in granting the Nottingham Lots in the northern part of the County below the fortieth parallel to some of his devoted followers did not help the sentiment regarding the boundary difficulties, nor did his grant of land to a company of Welsh Baptists in the vicinity of Iron Hill in the northeastern part of the County. It was supposed, and with very good reason, that these grants were made for the purpose of helping to establish land claims.
The dispute about the boundary line dragged on, aggravated by border troubles. Stringent commands from the King brought Lord Baltimore to a compromise. According to an agreement signed May 4, 1738, a temporary line was to be drawn beginning on the east fifteen and a quarter miles south of the parallel of Philadelphia to a point on the west side of the Susquehanna fourteen and three quarter miles south of the same parallel, thus settling the limits of both Provinces until the final determination of the boundary. It was not until 1768 when Mason and Dixon finished their work that the northern boundary was finally fixed.