The "Mason Dixon." line was commonly seen to separate what?
However, the original line was actually a boundary between Pennsylvania and Maryland used to settle an 80-year land dispute between the 2 colonies in the mid 1700s. It began when King Charles I, and King Charles II each granted land to separate colonists. The problem was that the description of the boundaries did not match.
It took Charles Mason and Jeremiah Dixon from 1763-1767 to survey the hundreds-of-miles long line.