The Mason–Dixon Line was surveyed between 1763 and 1767 by Charles Mason

Charles Mason

Charles Mason was an English astronomer who made significant contributions to 18th-century science and American history, particularly through his involvement with the survey of the Mason-Dixon line, which came to mark the division between the northern and southern United States...

 and Jeremiah Dixon

Jeremiah Dixon

Jeremiah Dixon was an English surveyor and astronomer who is perhaps best known for his work with Charles Mason, from 1763 to 1767, in determining what was later called the Mason-Dixon line....

 in the resolution of a border dispute between British colonies in Colonial America

Colonial America

The colonial history of the United States covers the history from the start of European settlement and especially the history of the thirteen colonies of Britain until they declared independence in 1776. In the late 16th century, England, France, Spain and the Netherlands launched major...

. It forms a demarcation line

Demarcation line

A demarcation line means simply a boundary around a specific area, but is commonly used to denote a temporary geopolitical border, often agreed upon as part of an armistice or ceasefire.See the following examples:...

 among four U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

s, forming part of the borders of Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

, Maryland

Maryland

Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...

, Delaware

Delaware

Delaware is a U.S. state located on the Atlantic Coast in the Mid-Atlantic region of the United States. It is bordered to the south and west by Maryland, and to the north by Pennsylvania...

, and West Virginia

West Virginia

West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...

 (then part of Virginia

Virginia

The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

). In popular usage, especially since the Missouri Compromise

Missouri Compromise

The Missouri Compromise was an agreement passed in 1820 between the pro-slavery and anti-slavery factions in the United States Congress, involving primarily the regulation of slavery in the western territories. It prohibited slavery in the former Louisiana Territory north of the parallel 36°30'...

 of 1820 (apparently the first official use of the term "Mason's and Dixon's Line"), the Mason–Dixon Line symbolizes a cultural boundary between the Northeastern United States

Northeastern United States

The Northeastern United States is a region of the United States as defined by the United States Census Bureau.-Composition:The region comprises nine states: the New England states of Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont; and the Mid-Atlantic states of New...

 and the Southern United States

Southern United States

The Southern United States—commonly referred to as the American South, Dixie, or simply the South—constitutes a large distinctive area in the southeastern and south-central United States...

 (Dixie

Dixie

Dixie is a nickname for the Southern United States.- Origin of the name :According to the Oxford English Dictionary, the origins of this nickname remain obscure. According to A Dictionary of Americanisms on Historical Principles , by Mitford M...

) and legality of slavery as a result, although the Missouri Compromise Line had much more definitive geographic connection to slavery in the United States leading up to the Civil War

History of the United States (1849–1865)

Industrialization went forward in the Northeast and a rail network linked the nation economically, opening up new markets. Immigration brought millions of European workers and farmers to the North...

.
Maryland's charter granted the land north of the entire length of the Potomac River

Potomac River

The Potomac River flows into the Chesapeake Bay, located along the mid-Atlantic coast of the United States. The river is approximately long, with a drainage area of about 14,700 square miles...

 up to the 40th parallel

40th parallel north

The 40th parallel north is a circle of latitude that is 40 degrees north of the Earth's equatorial plane. It crosses Europe, the Mediterranean Sea, Asia, the Pacific Ocean, North America, and the Atlantic Ocean....

.