How did the Mason-Dixon Line that divided the free states and slave states in the U.S. get its name?

The line that ended up symbolically delineating the border between the North and South was named after two British surveyors who were hired to settle a boundary dispute between Pennsylvania and Maryland in the 1760s.

Charles Mason and Jeremiah Dixon were astronomers by training, but their line proved to be more accurate than most surveyors’ lines of the time.

Although their east-to-west line marked the boundary between free states and slave states, their north-to-south line, set up at the same time, didn’t quite have the same symbolic impact.

It ended up being the boundary between Maryland and Delaware.