The original charters granted to the Penn and Calvert families stated unclearly the boundaries between the colonies of Pennsylvania and Maryland. The dispute caused considerable friction over the years and was eventually submitted to an English court. In 1760, the families compromised and selected two English astronomers, Charles Mason and Jeremiah Dixon, to survey the common border. In the years between 1763 and 1767, the surveyors ran a line west from the Delaware border for 244 miles. Every fifth milestone bore a replica of the Penn and Calvert coats of arms. The line was later extended to delineate the border between Pennsylvania and Virginia. In later times, the term "Mason-Dixon Line" connoted the boundary between slave and free states or between North and South.