Charles Mason and Jeremiah Dixon began the survey for the famous Mason-Dixon Line here, establishing the boundary that separates Delaware from Maryland, Pennsylvania, and New Jersey. The marker was settled in 1750 by John Emory and Thomas Jones of Maryland and John Watson and William Parson of Pennsylvania. It was intended to separate the lower three colonies of Pennsylvania, which later became the state of Delaware, from the state of Maryland. On the south side is the crest of Lord Baltimore, and on the opposite side is the crest of William Penn.