The Mason-Dixon Line is a historical boundary that was surveyed between 1763 and 1767 by Charles Mason and Jeremiah Dixon. It originally marked the border between the colonies of Pennsylvania and Maryland. Over time, it became associated with the cultural and political divide between the Northern and Southern United States, particularly regarding issues like slavery. The line is often referenced in discussions about the Civil War and regional differences in the U.S. Today, it symbolizes the division between the North and South, influencing perceptions of identity and culture in the eastern United States.