Мэйсон-Диксон шекарасы: Делавэр, Мэриленд және Пенсильвания арасындағы даулы территорияның шешімі

Surveyed border line between U. S. states of Delaware, Maryland, and Pennsylvania

The Mason–Dixon line, also called the Mason and Dixon line or Mason's and Dixon's line, is a demarcation line separating four U. S. states, constituting parts of the borders of Pennsylvania, Maryland, Delaware, and West Virginia (part of Virginia until 1863). It was surveyed between 1763 and 1767 by Charles Mason and Jeremiah Dixon as part of the resolution of a border dispute involving Maryland, Pennsylvania, and Delaware in the colonial United States. The dispute had its origins almost a century earlier in the somewhat confusing proprietary grants by King Charles I to Lord Baltimore (Maryland), and by his son King Charles II to William Penn (Pennsylvania and Delaware). The largest portion of the Mason–Dixon line, along the southern Pennsylvania border, later became informally known as the boundary between the Southern slave states and Northern free states. This usage came to prominence during the debate around the Missouri Compromise of 1820, when drawing boundaries between slave and free territory was an issue, and resurfaced during the American Civil War, with border states also coming into play. The Confederate States of America claimed the Virginia portion of the line as part of its northern border, although it never exercised meaningful control that far northespecially after West Virginia separated from Virginia and joined the Union as a separate state in 1863. It is still used today in the figurative sense of a line that separates the Northeast and South culturally, politically, and socially .

Maryland's charter of 1632 granted Cecil Calvert land north of the entire length of the Potomac River up to the 40th parallel. A problem arose when Charles II granted a charter for Pennsylvania in 1681. The grant defined Pennsylvania's southern border as identical to Maryland's northern border, but described it differently, as Charles relied on an inaccurate map. The terms of the grant clearly indicate that Charles II and William Penn believed the 40th parallel would intersect the Twelve Mile Circle around New Castle, Delaware, when in fact it falls north of the original boundaries of the City of Philadelphia, the site of which Penn had already selected for his colony's capital city. Negotiations ensued after the problem was discovered in 1681. A compromise proposed by Charles II in 1682, which might have resolved the issue, was undermined by Penn receiving the additional grant of the "Three Lower Counties" along Delaware Bay, which later became the Delaware Colony, a satellite of Pennsylvania. Maryland considered these lands part of its original grant. The conflict became more of an issue when settlement extended into the interior of the colonies. In 1732 the Proprietary Governor of Maryland, Charles Calvert, 5th Baron Baltimore, signed a provisional agreement with William Penn's sons, which drew a line somewhere in between and renounced the Calvert claim to Delaware. But later, Lord Baltimore claimed that the document he had signed did not contain the terms he had agreed to, and refused to put the agreement into effect. Beginning in the mid 1730s, violence erupted between settlers claiming various loyalties to Maryland and Pennsylvania. The border conflict would be known as Cresap's War. Progress was made after a Court of Chancery ruling affirming the 1732 agreement, but the issue remained unresolved until Frederick Calvert, 6th Baron Baltimore ceased contesting the claims on the Maryland side and accepted the earlier agreements. Maryland's border with Delaware was to be based on the Transpeninsular Line and the Twelve Mile Circle around New Castle. The Pennsylvania–Maryland border was defined as the line of latitude south of the southernmost house in Philadelphia (on what is today South Street). As part of the settlement, the Penns and Calverts commissioned the English team of Charles Mason and Jeremiah Dixon to survey the newly established boundaries between the Province of Pennsylvania, the Province of Maryland, and Delaware Colony. After Pennsylvania abolished slavery in 1781, the east–west part of this line and the Ohio River became a border between slave and free states, with Delaware retaining slavery until the 13th Amendment was ratified in 1865.

Mason and Dixon's actual survey line began to the south of Philadelphia, and extended from a benchmark east to the Delaware River and west to what was then the boundary with western 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. Mason and Dixon also confirmed the earlier survey delineating Delaware's southern boundary from the Atlantic Ocean to the "Middle Point" stone (along what is today known as the Transpeninsular Line). They proceeded nearly due north from this to the Pennsylvania border. The Maryland–Pennsylvania boundary is an east–west line with an approximate mean latitude of 39°43′20″ N (Datum WGS 84). In reality, the east west Mason–Dixon line is not a true straight line in the geometric sense, but is instead a polygonal chain, a series of many adjoining line segments, following a path between latitude 39°43′15″ N and 39°43′23″ N.

The surveyors also extended the boundary line west of Maryland's western boundary, into territory that was still in dispute between Pennsylvania and Virginia, though this was contrary to their original charter. In 1774, commissioners from Pennsylvania and Virginia met to negotiate their boundary, which at the time involved Pennsylvania's southern border west of Maryland and its entire western border. Both sides agreed that Pennsylvania's grant made its western border a tracing of the course of the Delaware River, displaced five degrees (approximately 265 miles) to the west. And both sides thought this would place Fort Pitt in Virginia territory (in fact it would not have). With that in mind, the governor of Pennsylvania argued that, despite the agreement reached with Maryland, Pennsylvania's southern border west of Maryland was still the 39th parallel, about south of the Mason–Dixon line. Negotiations continued for five years, with a series of proposed lines. In the end, a compromise was reached: the Mason–Dixon line would be extended west to a point five degrees west of the Delaware River. To compensate Pennsylvania for the claimed territory lost, its western boundary would be run due north rather than copying the course of the Delaware River. Crownstones included both coats of arms. Many of the original stones are still visible, resting on public land and protected by iron cages; a number have gone missing or were buried. The actual locations of the stones may differ a few hundred feet east or west from the exact positions where Mason and Dixon intended to place them, still, the line drawn from stone to stone forms the legal boundary. The lines have been resurveyed several times over the centuries without substantive changes to Mason's and Dixon's work, and additional benchmarks and survey markers were placed where necessary.

Mason and Dixon achieved a high level of accuracy in the survey due to the work of Nevil Maskelyne, some of whose instruments they used. There was keen interest in their work and much communication between the surveyors, Maskelyne and other members of the British Scientific establishment in the Royal Society in Britain, notably Henry Cavendish. During such survey work, it is normal to survey from point to point along the line and then survey back to the starting point, where if there were no errors the origin and re surveyed position would coincide. Normally the return errors would be randomi. e. the return survey errors compared to the intermediate points back to the start point would be spatially randomly distributed around the start point. Mason and Dixon found that there were larger than expected systematic errors, i. e. non random errors, that led the return survey consistently being in one direction away from the starting point. When this information got back to the Royal Society members, Henry Cavendish realised that this may have been due to the gravitational pull of the Allegheny Mountains deflecting the theodolite plumb bobs and spirit levels. Mason selected Schiehallion at which to conduct what became known as the Schiehallion experiment, which was carried out primarily by Maskelyne and determined the density of the Scottish mountain.

It is unlikely that Mason and Dixon ever heard the phrase "Mason–Dixon line". The official report on the survey, issued in 1768, did not even mention their names.

In popular usage to people from the United States, the Mason–Dixon line symbolizes a cultural boundary between the North and the South (Dixie). Originally "Mason and Dixon's Line" simply referred to the border between Pennsylvania (including "the Delaware Counties") and Maryland. However, it has been used metaphorically to describe the entire boundary between slave and free states during the 19th century. After Pennsylvania abolished slavery, it served as a demarcation line for the legality of slavery. Technically, that demarcation did not extend beyond Pennsylvania where Virginia, Maryland, and Delaware, all slave states, lay south or east of the boundary. Also lying north and east of the boundary was New Jersey, where slavery was formally abolished in 1846, but former slaves continued to be "apprenticed" to their masters until the passage of the Thirteenth Amendment to the United States Constitution in 1865. The Missouri Compromise line (Parallel 36°30′ north) had a much clearer geographic connection to slavery in the United States leading up to the Civil War.

Popular culture contains a multitude of references to the Mason–Dixon line as a general geographic division, or character names evoking it, although a minority of those specifically relate to the line itself.

Mason "The Line" Dixon is a leading character in Rocky Balboa (2006), the sixth film in the Rocky franchise, directed by and starring Sylvester Stallone. Played by real life boxer Antonio Tarver, Dixon is the current World Heavyweight Boxing Champion who is ridiculed for having never fought a real contender, and who thus agrees to an exhibition fight against the nearly 60 year old Rocky Balboa. In Attack of the Killer Tomatoes (1978), Mason Dixon is the leader of a government task force dedicated to stopping the worldwide crisis when tomatoes turn malignant.

The line makes several appearances in the 1953 Bugs Bunny cartoon "Southern Fried Rabbit". The line separates the drought affected North from which the "Yankee" Bugs leaves in search of carrots in the green lands of the "Dixie" South, the latter being guarded by Yosemite Sam, who thinks the Civil War is still ongoing.

In the regional baseball rivalry between the New York Yankees and the Boston Red Sox, the theoretical border that separates population centers that are majority Red Sox fans from majority Yankees fans in Connecticut is sometimes called the "Munson Nixon Line", in a (somewhat parodic) reference to the Mason–Dixon line. Credited to Steve Rushin of Sports Illustrated, This line has moved over the years, but it's still there.