Literally, the Mason-Dixon Line (or "Mason and Dixon's Line") demarcated state boundaries between the Province of Pennsylvania, the Province of Maryland, Delaware Colony and parts of Virginia Colony in colonial North America and between their successor-state members of the United States.
Symbolically, the line became the boundary between the North and South, particularly with respect to slavery. Pennsylvania abolished slavery early while Delaware and Maryland remained slave states until the American Civil War. In this sense, the "line" continued westward down the Ohio River to its confluence with the Mississippi River, then along the latter river to the northern boundary of Missouri.
Mason and Dixon's survey line begins south of Philadephia and extends from a benchmark east to the Delaware River and west to the border with West Virginia.
The surveyors also fixed the boundary between Delaware and Pennsylvania and the approximately north-south portion of the boundary between Delaware and Maryland. Most of the Delaware-Pennsylvania boundary is an arc, and the Delaware-Maryland boundary does not run truly north-south because it was intended to bisect the Delmarva Peninsula rather than follow a meridian. However, the Maryland-Pennsylvania boundary is a true east-west line. The line also traced the border between Pennsylvania and West Virginia (originally part of Virginia).
The Mason-Dixon line is marked in places by benchmarks and survey stones, many of which have been lost.
The original line was established to end a boundary dispute between the British colonies of Maryland and Pennsylvania. Due to incorrect maps and confusing legal descriptions, the royal charters of the two colonies overlapped. Maryland was granted the territory north of the Potomac River up to the fortieth parallel; Pennsylvania was granted land extending northward from a point "12 miles north of New Castle Towne", which is located below the fortieth parallel. The most serious problem was that the Maryland claim would put Philadelphia, which became the major city in Pennsylvania, within Maryland. A protracted legal dispute between the Calvert family, which controlled Maryland, and the Penn family, which controlled Pennsylvania, was ended by the 1750 ruling that the boundary should be fixed at the latitude 39°43' north (15 miles south of Philadelphia). The disputants engaged an expert British team, astronomer Charles Mason and surveyor Jeremiah Dixon, to survey what became known as the Mason-Dixon line.
After completing surveys for the DelMarVa boundary between Delaware and Maryland, and the unique circular boundary between Pennsylvania and Delaware centered on New Castle, between 1763 and 1767 they ran the more famous Maryland-Pennsylvania line for 244 miles (392 kilometres) (just 36 miles short of the legal terminus), until a group of Native Americans forced them to quit their progress westwards. This boundary between Pennsylvania and Maryland was resurveyed in 1849, then again in 1900.
The Missouri Compromise of 1820 created the political conditions which made the Mason-Dixon line important to the history of slavery.
On November 14, 1963, during the bicentennial of the Mason-Dixon Line, U.S. President John F. Kennedy opened a newly completed section of Interstate 95 where it crossed the Maryland-Delaware border. It was to be his last public appearance before his assassination in Dallas, Texas 8 days later. The Delaware Turnpike and the Maryland portion of the new road were each later designated as the John F. Kennedy Memorial Highway.
- Mason-Dixon Line (http://freespace.virgin.net/john.cletheroe/usa_can/usa/mas_dix.htm)
- Mason & Dixon, Thomas Pynchon. Picador, 2004. ISBN 0312423209.
- the Charter of Maryland (http://www.yale.edu/lawweb/avalon/states/ma01.htm) (1632)
- Charter for the Province of Pennsylvania (http://www.yale.edu/lawweb/avalon/states/pa01.htm) (1681)