On October 18, 1767, Charles Mason and Jeremiah Dixon complete their survey of the boundary between the colonies of Pennsylvania and Maryland as well as areas that would eventually become the states of Delaware and West Virginia. The Penn and Calvert families had hired Mason and Dixon, English surveyors, to settle their dispute over the boundary between their two proprietary colonies, Pennsylvania and Maryland.
In 1760, tired of border violence between the colonies’ settlers, the British crown demanded that the parties involved hold to an agreement reached in 1732. As part of Maryland and Pennsylvania’s adherence to this royal command, Mason and Dixon were asked to determine the exact whereabouts of the boundary between the two colonies. Though both colonies claimed the area between the 39th and 40th parallel, what is now referred to as the Mason-Dixon line finally settled the boundary at a northern latitude of 39 degrees and 43 minutes. The line was marked using stones, with Pennsylvania’s crest on one side and Maryland’s on the other.