Completion of the Mason–Dixon Line survey

The English team of astronomer Charles Mason and surveyor Jeremiah Dixon surveyed the boundary between the Province of Pennsylvania, the Province of Maryland, and Delaware Colony between 1763 and 1767, as part of the resolution to Cresap's War. Their line began south of Philadelphia and extended from a benchmark east to the Delaware River and west to what was then the boundary with western Virginia. The survey was finished on October 19, 1767, about 31 miles east of what is now Pennsylvania's southwest corner, at a point that became known as the Mason and Dixon Survey Terminal Point. The line was marked with stones every mile and crownstones every five miles, using stone shipped from England.