Mason-Dixon line Brown's Hill #8540 B&W
Up Brown's Hill, they climbed in October 1767. English astronomers Charles Mason and Jeremiah Dixon had been hired in 1763 as surveyors "to settle an 82-year boundary dispute between the Penns and Calverts, who had received royal grants in America," according to the Mason-Dixon Historical Park website.
When they reached a point just up Brown's Hill, from this location on the hill at Mason-Dixon Historical Park in Core, W.Va., seen here on November 14, 2023, their native American guides informed them they could go no further, as there was a warpath that they could cross, and so their survey ended 23 miles short of their goal.
The Mason-Dixon Line determined part of the borders of four states, Delaware, Maryland, Pennsylvania, and West Virginia, and "later became informally known as the boundary between the Southern slave states and Northern free states," according to Wikipedia.