Did you know The Mason Dixon Line is actually a survey line?
Charles Mason, an assistant astronomer at Greenwich Observatory, and Jeremiah Dixon, an astronomer, mathematician, and surveyor, were hired to survey an agreed-upon line to settle a dispute between the Pennsylvania and Maryland British colonies. Starting in 1763, it took 4 years and cost $75,000 to run the 233-mile line. Modern surveys have shown it to be an accurate survey, within a couple of seconds of latitude. Today, the Mason Dixon line forms part of the borders of four states: Pennsylvania, Maryland, Delaware, and West Virginia!
(Info gathered from Britannica)