a brief history of the mason-dixon survey line

8/14/2019 A Brief History of the Mason-Dixon Survey Line

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A brief history of the Mason-Dixon survey line

John Mackenzie

College of Agriculture & Natural ResourcesUniversity of Delaware

Newark, DE 19717

In 1763-67 Charles Mason and Jeremiah Dixon surveyed and marked most of the boundaries between Maryland, Pennsylvania and the Three Lower Counties that becameDelaware. The survey, commissioned by the Penn and Calvert families to settle their long-running boundary dispute, provides an interesting reference point in the region’shistory. This paper summarizes the background of the boundary dispute, the execution of

Mason and Dixon’s survey, and the symbolic role of the Mason-Dixon Line in Americancivil rights history.

Historical background

When George Calvert (Figure 1), England’s Secretary of State under King JamesI, publicly declared his Catholicism in 1625, English law required that he resign. James

awarded him an Irish baronetcy, making him the first Lord Baltimore. Although Calvertwas an investor in the Virginia Company, he was barred from Virginia because of hisreligion. He then started his own “Avalon” colony in Newfoundland, but the climate proved inhospitable. So Calvert persuaded James’s successor, Charles I, to grant hisfamily the land north of the Virginia colony that became Maryland.

The 1632 grant gave the Calverts everything north of the Potomac to the 40th

parallel, and from the Atlantic west to the source of the Potomac. George Calvert diedlater in 1632, and his sons started the Maryland colony, named in honor of Charles I’s

consort Henrietta Maria. On May 27

th

1634, Leonard Calvert and about 300 settlersarrived in the Chesapeake Bay at St. Mary’s (Figure 2)

While the Calverts were settling on the Chesapeake Bay, Swedish colonistsarrived in the Delaware Bay (named in 1610 by Captain Samuel Argail in honor of

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Thomas West, Lord de la Warr, the governor of the Jamestown colony). The Swedesestablished Fort Christina at what is now Wilmington in 1638.

The 1642 revolution in England stalled English colonial expansion. DuringEngland’s Parliamentary Commonwealth period, Dutch soldiers from New Amsterdam(Manhattan) captured Fort Christina in 1651. Dutch colonial governor Peter Stuyvesant purchased the land between the Christina River and Bombay Hook from the Indians, and built Fort Casimir at what is now New Castle. Following the first English-Dutch war (1652-54), the Swedes captured Fort Casimir, but the Dutch reestablished local control in1656.

English colonial expansion resumed after the Restoration brought Charles II to the

English throne. In 1664 the Duke of York, Charles II’s brother James, captured NewAmsterdam, renaming it New York, and seized the Swedish-Dutch colonies on theDelaware River as well. The Dutch briefly recaptured New York in 1673, but after their 1674 defeat in Europe in the third Dutch War, they ceded all their American claims toEngland in the Treaty of Westminster. Having regained his American territories, theDuke of York granted the land between the Hudson and Delaware rivers to his friendsGeorge Carteret and John Berkeley in 1675, and they established the colony of NewJersey.

Sir William Penn had served the Duke of York in the Dutch wars, and had loanedthe crown about £16,000. His son William Penn (Figure 3) who had become a Quaker, petitioned Charles for a grant of land north of the Maryland colony as repayment of thedebt. In 1681 Charles granted Penn all the land extending five degrees west from theDelaware River between the 40th and 43rd parallels, excluding the lands held by the Dukeof York within a “twelve-mile circle” centered on New Castle, plus the lands extendingsouthward—the recaptured Dutch and Swedish colonies. Was this to be a twelve-mileradius circle, or a twelve-mile diameter circle, or maybe a twelve-mile circumferencecircle?—the language was unclear. And even the twelve-mile radius circle lies entirely below the 40th parallel. The Calvert family had ample opportunity to get the 40th parallelsurveyed and marked, but never bothered to do so. Philadelphia itself was south of the

40

th

parallel, at the upper limit of deep-water navigability on the Delaware, andPennsylvanian colonists were rapidly settling to the west and south of the city. Insomewhat un-Quakerly fashion, Penn took maximum advantage of every ambiguity.

Penn needed to get his colony better access to the Atlantic, and in 1682 he leasedthe Duke of York’s lands from New Castle down to Cape Henlopen. Penn arrived in





New Castle in October 1682 to take official possession of the “Three Lower Counties” onthe Delaware Bay. He renamed St. Jones County to Kent County, and Deale County toSussex County, and the Three Lower Counties were annexed to the Pennsylvania colony.

Penn negotiated with the third Lord Baltimore at the end of 1682 at Annapolis,and in April 1683 at New Castle, to establish and mark a formal boundary betweenMaryland and Pennsylvania including the Lower Three Counties. The Calverts wanted todetermine the 40th parallel by astronomical survey, while Penn suggested measuringnorthward from the southern tip of the Delmarva peninsula (about 37o 5’ N), assuming 60miles per degree as Charles II had suggested. (The true distance of one degree of latitudeis about 69 miles.) This would give Pennsylvania the uppermost part of the Chesapeake.

After the negotiations failed, Penn took his case to the Commission for Trade andPlantations. In 1685 the Commission determined that the land lying north of CapeHenlopen between the Delaware Bay and the Chesapeake should be divided equally; thewestern half belonged to the Calverts, while the eastern half belonged to the crown, i.e.,to the Duke of York, and thus to Pennsylvania under Penn’s lease. The boundary between Maryland and the Three Lower Counties was now legally defined, but the east-west boundary between Pennsylvania and Maryland remained unresolved.

Charles II died in 1685, and the Duke of York, a Catholic convert, succeeded him

as James II. But three years later, William of Orange, the Dutch grandson of Charles Iand husband of James II’s protestant daughter Mary, seized the English throne. TheCalverts lost control of their Maryland holdings, and Maryland was declared a royalcolony. Penn’s ownership of Pennsylvania and the Lower Three Counties was alsosuspended from 1691 to 1694. The Calverts did not regain their proprietorship of Maryland until 1713 when Charles Calvert, the fifth Lord Baltimore, renouncedCatholicism.

Penn revisited America in 1699-1701, and reluctantly granted Pennsylvania and

the Lower Three Counties separate elected legislatures. He also commissioned localsurveyors Thomas Pierson and Isaac Taylor to survey and demarcate the twelve-mileradius arc boundary between New Castle and Chester counties. Pierson and Taylor completed the survey in ten days using just a chain and compass. The survey marks weretree blazes, and once these disappeared, the location of the arc boundary was mostly amatter of fuzzy recall and conjecture.



Geodetic science was in its infancy. Latitude could be estimated reasonablyaccurately with sextant and compass, but longitude was largely guesswork. As England’snaval power and colonial holdings continued to expand, the demand for better maps andnavigation intensified. Parliament set a prize of £20,000 for a solution to the “longitude problem” in 1712. The challenge was to determine a longitude in the West Indies

onboard a ship with less than half a degree of longitude error. Dava Sobel’s book Longitude (1996) details how clock-maker John Harrison eventually won the prize withhis “H4” precision chronometer.

Penn died in 1718, disinheriting his alcoholic eldest son William Jr., and leavingthe colonies to his second wife Hannah, who transferred the lands to her sons Thomas,John, Richard and Dennis. Thomas outlived the others and accumulated a two-thirdsinterest in the holdings.

In 1731, the fifth Lord Baltimore petitioned King George II for an officialresolution of the boundary dispute. In the ensuing negotiations the Calverts tried to holdout for the 40th parallel, but Pennsylvania colonists had settled enough land to the westand southward of Philadelphia that this was no longer practical. In 1732 the partiesagreed that the boundary line should run east from Cape Henlopen to the midpoint of the peninsula, then north to a tangency with the west side of the twelve-mile radius arcaround New Castle, then around the arc to its northernmost point, then due north to aneast-west line 15 miles south of Philadelphia. It was a bad deal for the Calverts. Theeast-west line would turn out to be about 19 miles south of the 40th parallel, and, as the

map (Figure 5) appended to the agreement shows, would intersect the arc. The map placed “Cape Hinlopen” at what is now Fenwick Island, almost 20 miles to the south aswell; this error was an attempt at deception, not ignorance (compare the map in Figure 4,completed more that 50 years earlier). But litigation over interpretation and detailsdragged on.

The border conflict led to sporadic local violence. In 1736 a mob of Pennsylvanians attacked a Maryland farmstead. A survey party commissioned by theCalverts was run off by another mob in 1743.

In 1750, the Court of Chancery established a bipartisan commission to survey andmark the boundaries per the 1732 agreement. The commissioners hired local surveyorsto mark an east-west transpeninsular line from Fenwick Island to the Chesapeake in1750-51, and then determine the middle point of this line, which would mark thesouthwest corner of the Three Lower Counties. As the survey team worked from








Fenwick Island westward the rivers, swamps and dense vegetation made the work difficult, and there were continuing disputes, e.g., should distances be determined byhorizontal measures or on the slopes of the terrain? Should the transpeninsular line stopat the Slaughter Creek estuary or continue across that peninsula, known as Taylor’sIsland, to the open Chesapeake? Should the line stop at the inundated marsh line of the

Chesapeake or at open water?

The transpeninsular survey and its middle point were not officially approved inLondon until 1760. In 1761, the colonial surveyors began running the north-south“tangency” line from the middle point toward a target tangent point on the twelve-milearc. With poor equipment and some miscalculations, their first try at a tangency line passed a half-mile east of the target point on the arc. Their second try was 350 yards tothe west. The disputants required much higher standards of accuracy, and they consultedthe royal astronomer James Bradley at the Greenwich observatory for advice on getting

the survey done right.



The Mason and Dixon survey

Bradley recommended Charles Mason and Jeremiah Dixon to complete the boundary survey. Mason was Bradley’s assistant at the observatory, an Anglicanwidower with two sons. Dixon was a skilled surveyor from Durham, a Quaker bachelor whose Meeting had ousted him for his unwillingness to abstain from liquor. In 1761Mason and Dixon had sailed together for Sumatra, but only made it to the Cape of GoodHope, to record a transit of Venus across the sun to support the Royal Society’scalculations of distance by parallax between the Earth and sun. Their major tasks inAmerica would be to survey an exact tangent line running northward from the middle point of the transpeninsular line to a tangent point on the twelve-mile arc boundaryaround New Castle; the east-west boundary line running five degrees of longitudewestward from the Delaware River along a line (actually an arc on the earth's surface) of

latitude passing fifteen miles south of the southernmost part of Philadelphia; and thenorth line from the arc tangency to a perpendicular intersection with the west line ( Figure6). It would be one of the great technological feats of the century

Mason and Dixon arrived in Philadelphia on November 15 th 1763 during a tense period. The Seven Years’ War had spilled over to North America as the French andIndian Wars, and although the Treaty of Paris, signed in February 1763, had put anofficial end to the hostilities, conflicts between colonists and Indians continued. TheIroquois League, or Six Nations (Mohawk, Onondaga, Cayuga, Seneca, Oneida and

Tuscarora), had supported the British against their longtime enemies, the Cherokee,Huron, Algonquin and Ottawa, whom the French had supported in their attacks oncolonists. Pontiac, chief of the Ottawa, had organized a large-scale attack on Fort Detroiton May 5th 1763, and some 200 settlers were massacred along the western frontier.

Local reaction to the news was brutal. In Lancaster, Pennsylvania, a mob of mostly Scots-Irish immigrants known as the “Paxton boys” attacked a small ConestogaIndian village in December, hacked their victims to death and scalping them. Theremaining Conestogas were brought to the town jail for protection, but when the mob

attacked the jail the regiment assigned to protect the Indians did nothing to stop them.The helpless Indians—men, women and children—were all hacked to pieces and scalpedin their cells. The Paxton Boys then went after local Moravian Indians, who were takento Philadelphia for protection. Enraged that the government would “protect Indians butnot settlers,” about 500 Paxton Boys actually invaded Philadelphia on February 6, 1764,although Benjamin Franklin was able to calm the mob. Mason and Dixon were shockedat the violence, and Mason would visit the scene of the Lancaster murders a year later.







As the survey progressed, racial violence and the relentless dispossession of Indians werefrequent background themes.

Mason had brought along state-of-the-art equipment for the survey. This includeda “transit and equal altitude instrument,” a telescope with cross-hairs, mounted with precision adjustment screws, to sight exact horizontal points using a mounted spirit level,and also to determine true north by tracking stars to their maximum heights in the skywhere they crossed the meridian. The famous “zenith sector,” built by Londoninstrument-maker John Bird, was a six-foot telescope mounted on a six-foot radius protractor scale, with fine tangent screws to adjust its position; it was used to measure theangles of reference stars from the zenith of the sky as they crossed the meridian. Thesemeasurements could be compared against published measurements of the same stars’angles of declination at the equator to determine latitude. These were more reliable thanmeasurements of azimuth against a plumb bob, which were already known to be subject

to local gravitational anomalies. The zenith sector traveled on a mattress laid on a cartwith a spring suspension.

Mason and Dixon also brought a Hadley quadrant, used to measure angular distances; high-quality survey telescopes; 66-foot long Gunter chains comprised of 100links each (1 chain = 4 rods; 1 chain ×10 chains = 1 acre; 80 chains = 1 mile), along witha precision brass measure to calibrate the chain lengths; and wood measuring rods or “levels” to measure level distances across sloping ground. A large wooden chestcontained a collection of star almanacs, seven-figure logarithm tables, trigonometric

tables and other reference materials; Mason was skilled at spherical trigonometry.

Mason had acquired a precision clock so that the local times of predictedastronomical events could be compared against published Greenwich times. Each one-minute local time difference implies a 15-second longitude difference. John Harrison’s“H4” chronometer had sailed to Jamaica and back in 1761, losing only 39 seconds on theround trip; the longitude calculations in Jamaica based on his clock were well within theaccuracy standards Parliament had set for the £20,000 longitude prize. But NevilMaskelyne, who had succeeded Bradley as royal astronomer, and the Royal Society

remained skeptical about the reliability of chronometers in complementing astronomicalcalculations of longitude. Maskelyne insisted on the superiority of a purely astronomicalapproach, a computationally complex “lunar distance” method based on angular distances between the moon and various reference stars. Harrison wouldn’t collect his entire prizeuntil 1773. Mason and Dixon would test the reliability of chronometric positioning,although Mason was skeptical of it.



The southernmost part of Philadelphia was determined by the surveycommissioners to be the north wall of a house on the south side of Cedar Street (theaddress is now 30 South Street) near Second Street. Mason and Dixon had a temporaryobservatory erected 55 yards northwest of the house, and after detailed celestialobservations and calculations, they determined the latitude of the house wall to be

39o

56’29.1”N.

Since going straight south would take them through the Delaware River, they thensurveyed and measured an arbitrary distance (31 miles) west to a farm owned by JohnHarland (Figure 7) in Embreeville, Pennsylvania, at the “Forks of the Brandywine.”They negotiated with Harland to set up an observatory, and set a reference stone, nowknown as the Stargazers' Stone (Figure 8), at the same latitude. They spent the winter atHarland’s farm making astronomical observations on clear nights and enjoying localtaverns on cloudy nights. The Harland house still stands at the intersection of

Embreeville and Stargazer Roads, and the Stargazers' Stone is in a stone enclosure just upStargazer Road on the right. Its latitude is 39o56’18 9” N which they calculated to be356.8 yards to south of the parallel determined in Philadelphia.

At Harland’s they observed and timed predicted transits of Jupiter’s moons, aswell as a lunar eclipse on March 17th 1764. The average (sun) time of these events at theStargazers’ Stone was 5 hours 12 minutes and 54 seconds earlier than published predictedtimes for the Paris observatory (longitude 2o20’14”E). So they were able to estimate their longitude as (5:12:54)/(24:00:00) x 360o = 78o13’30 west of Paris, and thus 78o13’30” -

2

o

20’14” = 75

o

53’6” west of Greenwich. They published these findings in the RoyalSociety’s Philosophical Transactions in 1769.

The clock used in this experiment was actually 37 seconds fast, so at fifteen arcseconds of longitude per clock second, their calculated longitude was 9’15” or abouteight miles too far west. That was more accurate than Parliament’s longitude prize hadrequired, but the margin of error was still a thousand times larger than the margin of error in their latitude calculations. Fortunately, Mason and Dixon’s principal tasks involvedmore local positioning than global positioning. They proposed measuring a degree of

longitude for the Royal Society as part of their survey of the parallel betweenPennsylvania and Maryland; although the Society never funded that project, it wouldfund their measurement of a degree of latitude in 1768.

In the spring of 1764 the survey party ran a line due south from Harland’s farm,measured with the survey chains and levels, with a team of axmen clearing a “visto” or







line of sight eight or nine yards wide the entire way. They arrived in April 1764 at a farmfield owned by Alexander Bryan in what is now the Possum Hill section of Delaware’sWhite Clay Creek State Park. They placed an oak post called “Post mark’d West” at alatitude of 39o43’ 26.4”N, after verifying that this point was exactly 15 miles below the39o56’29.1”N latitude they had determined in Philadelphia. This point is now marked by

a stone monument (Figure 9) accessible by a short spur trail off the Bryan’s Field trail,about 600 yards downhill (due south) from the ruins of the farmstead. The easiest access point is from the east (gravel road) parking lot at Possum Hill off Paper Mill Road. ThePost mark’d West would be the eastern origin and reference latitude point for the westline.

Mason and Dixon then headed south to the middle point of the transpeninsular line that the colonial surveyors had marked, and they spent the rest of 1764 surveying thenorth-south boundary line. With a team of axmen clearing the vistos ahead of them, they

resurveyed and marked the tangency line northward from the middle point toward thetarget tangency point on twelve-mile arc 82 miles to the north (Figure 11b). Theycrossed the Nanticoke River, Marshyhope Creek, Choptank River, Bohemia River, andBroad Creek. Where their survey chains could not span a river, they measured the river width by triangulation, using the Hadley quadrant on its side to calculate the angle between two points on the opposite side. They arrived at the 82-mile point in August1764.

Mason and Dixon then ran an exact twelve-mile line from the New Castle

courthouse to the tangency line, setting the tangent point marker at the 82-mile point of the tangency line; this is located by a small drainage pond at the edge of an apartmentcomplex, south of the Delaware-Maryland boundary on Elkton Road and just north of therail lines (Figure 9; the smaller, rounded stone is the marker placed by Mason andDixon.). This point was 17 chains and 25 links west of the tangency point targeted by the1761 survey. Since the tangency line runs slightly west of true north, the tangent pointlies south and slightly east of the arc’s westernmost point (Figure 6).

After joining the tangency line perpendicularly to the twelve-mile radius line from

New Castle in August 1764, they returned south to the middle point, checking andcorrecting marks as they went. On this re-check, their final error at the middle point,after 82 miles, was 26 inches. They returned north again, making final placements of themarks into November. During this phase of the survey, their base of operations inDelaware was St. Patrick’s Tavern in Newark, where the Deer Park Tavern now stands.Tavern scenes in Thomas Pynchon’s 1997 novel Mason & Dixon are consistent with atleast one contemporary account of their enjoyment of the taproom. In January 1765


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Mason visited Lancaster (and the jail where the Tuscaroras had been slaughtered) and“Pechway” (Pequa). In February, he toured Princeton NJ and New York.

Mason and Dixon began the survey of the west line from the “Post mark’d West”in April 1765. The Arc Corner Monument, placed in 1892 (Figure 9), is located at thenorth side of the W.S. Carpenter Recreation Area of White Clay Creek State Park just off Hopkins Bridge Road, and marks the intersection of the west line with the 12-mile arc.Mason and Dixon spent the next couple of years surveying this line westward. Again,their axmen cleared vistos, generally eight yards wide. They would survey straight 12-mile line segments, starting at headings about 9 minutes northward of true west andsighting linear chords to the true latitude curve, then make detailed astronomicalcalculations to adjust the intermediate mile mark southward to the exact 39 o 43’ 17.4” Nlatitude. The true latitude is not a straight line: looking westward in the northernhemisphere it gradually curves to the right. It was exacting work.

The survey crossed the two branches of the Christina Creek, the Elk River, andthe winding Octoraro several times. The survey party reached the Susquehanna in May1765 (Figure 11c).

At the end of May they interrupted the survey of the west line, and returned to Newark to survey the north line from the tangent point through the western edge of the

12-mile arc to its intersection with the west line (Figure 6). From the tangent point, thesurvey proceeded due north, intersecting the arc boundary again about a mile and a half further up at a point now marked by an “intersection stone.” The location is behind theDuPont Company’s Stine-Haskell labs north of Elkton Road very near the Conrail railline. The north line ended at a perpendicular intersection with the west line in a tobaccofield owned by Captain John Singleton. This is the northeast corner of Maryland, nowknown as the Tri-State marker.

The boundaries between Maryland and the Three Lower Counties were now

complete. The locations of the final mile points on the tangent and north lines, and thediscernible inflections of the Maryland/Delaware boundary at the tangent point, areshown on the Newark West 7.5-minute USGS topographic map. The tri-state marker (Figure 9) is located about 150 meters east of Rt. 896 behind a blue industrial building atthe MD/PA boundary. The thin sliver of land (secant) west of the North Line but withinthe 12-mile arc west of the North Line was assigned to New Castle County (PA, now DE) per the 1732 agreement. The “Wedge” between the North Line and the 12-mile arc just


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below the West Line was assigned to Chester County, PA, but later ceded to Delaware(Figure 6).

In June 1765 Mason and Dixon reported their progress to the surveycommissioners representing the Penn and Calvert families at Christiana Bridge (now thevillage of Christiana). They then resumed the survey of the west line from theSusquehanna. As they went along, the locals learned whether they were Marylanders or Pennsylvanians. They reached South Mountain (mile 61, Figure 11d) at the end of August, crossed Antietam Creek and the Potomac River in late September, and continuedwestward to North (aka Cove) Mountain near Mercersburg PA in late October,completing a total of 117 miles of the west line that year. From the summit of NorthMountain they could see that their west line would pass about two miles north of thenorthernmost bend in the Potomac. Had the Potomac looped further north intoPennsylvania, the western piece of Maryland would have been cut off from the rest of the

colony.

The survey party stored their instruments at the house of a Captain Shelby near North Mountain, and returned east in the fall, checking and resetting their marks. In November 1765 they returned to the middle point to place the first 50 mile markers alongthe tangent line (Figure 10). These had been quarried and carved in England, and weredelivered via the Nanticoke and Choptank rivers. Crownstones with the Penn and Calvertcoats of arms were placed every five miles; regular milestones with "P" and "M"markings were placed at intervening miles. They spent January 1766 at the Harland

farm. In February and March, Mason traveled “for curiosity” to York PA; Frederick MD;Alexandria, Port Royal, Williamsburg and Annapolis VA.

The survey party rendezvoused at North Mountain in March 1766 and resumedthe survey from there, reaching Sideling Hill at mile 135 at the end of April. There werelong periods of rain and snow through late April. West of Sideling Hill was almostunbroken wilderness, and the wagons with the marker stones couldn’t make it over themountain so they marked with oak posts from there onward. They reached mile 165 inJune, near the eastern continental divide, and spent the rest of the summer backtracking

for corrections and final placement of marks. Mason noted the gradual curvature of thevisto along the latitude, as seen from several summits including the top of SouthMountain:

From any Eminence in the Line where 15 or 20 Miles of the Visto can be seen (of

which there are many): The said Line or Visto very apparently shows itself to


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form a Parallel of Northern Latitude. The Line is measured Horizontal; the Hillsand Mountains measured with a 16 ½ feet Level and besides the Mile Posts; we

have set Posts in the true Line, marked W, on the West side, all along the Line

opposite the Stationary Points where the Sector and Transit Instrument stood.

The said Posts stand in the Middle of the Visto; which in general is about Eight

yards wide. The number of Posts set in the West Line is 303. ( Journal entry for 25 September 1766)

Back in Newark in October, they got permission from the commissioners to measurethe distance of a degree of latitude as a side project for the Royal Society. They returnedto the middle point of the transpeninsular line for astronomical observations in preparation for this, then returned to Newark and began setting 100 stone mile markersalong tangent and west lines. The stones in the west line were set at mile intervalsstarting from the northeast corner of Maryland. At the end of November they measured

the eastward extension of the west line from the Post mark’d West across Pike, Mill, RedClay and Christiana (Christina) creeks to the Delaware River.

They spent parts of the winter of 1766-67 at Harland’s farm making astronomicalobservations, using a clock on loan from the Royal Society to time ephemera. Masonspent the late winter and early spring traveling through Pennsylvania, Maryland andVirginia. He met the chief of the Tuscaroras in Williamsburg.

The survey was supposed to extend a full five degrees of longitude (about 265miles) to the west, but the Iroquois wanted the survey stopped. Negotiations between theSix Nations and William Johnson, the commissioner of Indian Affairs, lasted well into1767. After a payment of £500 to the Indians, Mason and Dixon finally got authorizationin June 1767 to continue the survey from the forks of the Potomac near Cumberland.They started out with more than 100 men that summer, including an Indian escort partyand a translator, Hugh Crawford, as they continued the survey westward from mile 162.

A.H. Mason’s edition of the survey journal (1969) includes a long undatedmemorandum written by Mason describing the terrain crossed by the west line. West of the Monongahela they met Catfish, a Delaware; then a party of Seneca warriors on a raidagainst the Cherokees; then Prisqueetom, an 86-year-old Delaware who “had a greatmind to go and see the great King over the Waters; and make a perpetual Peace with him; but was afraid he should not be sent back to his own Country.” The memorandumincludes Crawford’s detailed descriptions of the Allegheny, Ohio and Mississippi riversand many of their tributaries.



As the survey party opened the visto further westward, the Indians grewincreasingly resentful of the intrusion into their lands. The survey team reached mile 219at the Monongahela River in September. Twenty-six men quit the crew in fear of

reprisals from Indians, leaving only fifteen axmen to continue clearing vistos for thesurvey until additional axmen could be sent from Fort Cumberland. On October 9th, 231miles from the Post mark’d West, the survey crossed the Great Warrior Path, the principal north-south Indian footpath in eastern North America (Figure 11e). TheMohawks accompanying the survey said the warpath was the western extent of thecommission with the chiefs of the Six Nations, and insisted the survey be terminatedthere. Realizing they had gone as far as they could, Mason and Dixon set up their zenithsector and corrected their latitude, and backtracked about 25 miles to reset their lastmarks. They left a stone pyramid at the westernmost point of their survey, 233 miles 17chains and 48 links west of the Post mark’d West in Bryan’s field.

Mason and Dixon returned east, arriving back at Bryan’s farm on December 9th

1767, and reported their work to the commissioners at Christiana Bridge later thatmonth. They had hoped the Royal Society would sponsor a measurement of a degree of longitude along the west line, but that proposal was never approved. Mason calculatedthat if the earth were a perfect spheroid of uniform density (which it is not) themeasurement would be 53.5549 miles.

They spent about four months in early 1768 working on the latitude measurement project for the Royal society, using high-precision measuring levels with adjustments for temperature. They worked their way southward from the tangent point reaching themiddle point in early June 1768, then working northward again. In Mason’s finalcalculation, published in the Royal Society’s Philosophical Transactions in 1768, adegree of latitude on the Delmarva Peninsula from the middle point northward was68.7291 miles.

On August 16th 1768 they delivered 200 printed copies of the map (Figure 11a

shows the eastern half) of their surveys, as drawn by Dixon, to the commissioners at ameeting at New Town on the Chester River. They were elected to the AmericanPhilosophical Society in April 1768. After settling their accounts, they enjoyed ten daysof socializing in Philadelphia and then left for New York, sailing on the Halifax Packet toFalmouth, England, on September 11th 1768.

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Mason and Dixon never worked together again. In May 1769 the Royal Societysent Dixon to Hammerfest, above the Arctic Circle in Norway, and Mason to Cavan,Ireland, to record the June 4th transit of Venus, which occurred simultaneously with alunar eclipse. David Rittenhouse and members of the American Philosophical Societyconducted simultaneous observations in America.

Dixon was elected a fellow of the Royal Society in 1773. He remained a bachelor, retired to Cockfield, Durham, and died in 1779 at age 45.

Mason remarried in 1770, and continued to work for Nevil Maskelyne at theRoyal Observatory, although he was never elected to the Royal Society. He returned toPhiladelphia with his second wife and eight children in July 1786, died there on October

25

th

, and was buried in the Christ Church burial ground on Arch Street. His widow andher six children returned to England. His two sons from his first marriage remained inAmerica.

Less than a decade after the 1763-67 survey settled their long-running boundarydispute, the Penns and Calverts lost their colonies to the American Revolution. Masonand Dixon’s tangent, north and west lines became the boundaries between the new statesof Delaware, Maryland and Pennsylvania.

The Mason-Dixon Line

The west line would not become famous as the “Mason-Dixon Line” for another fifty years as America slowly and haltingly addressed longstanding inequities in civilrights.

In the east, the piedmont Lenni Lenape tribes of Delaware and Pennsylvania werecompletely dispossessed, and the remnants of the tribes were eventually relocated by aseries of forced marches: to Ohio, Indiana, Missouri, Kansas, and finally to the IndianTerritory which became Oklahoma. Hannah Freeman (1730-1802), known as “IndianHannah,” was the last of the Lenni Lenape in Chester County, Pennsylvania.



The tidewater Nanticoke communities were dispersed from Delaware andMaryland by 1750, and the last tribal speaker of the Nanticoke, Lydia Clark, died before1850. Some migrated as far north as Canada and were assimilated into other tribes, andsome were relocated west. The remnant that remains in the area holds an inter-tribal pow-wow each September in Sussex County.

With Indians almost entirely displaced from the eastern states, the national debatefocused on slavery and abolition, and whether new states entering the Union should befree or slave states. The Missouri Compromise of 1820 designated Mason and Dixon’swest line as the national divide between the “free” and “slave” states east of the OhioRiver, and the line suddenly acquired new significance.

Delaware’s 1776 state constitution had banned the importation of slaves, and statelegislation in 1797 effectively stopped the export of slaves by declaring exported slavesautomatically free. The state’s population in the 1790 census was 15 percent black, andonly 30 percent of these were free blacks. By the 1820 census, 78 percent of Delaware’s blacks were free. By 1840, 87 percent were free.

Both escaped slaves and legally free blacks living anywhere near the line werevulnerable to kidnapping by slave-catchers operating out of Maryland. One of the mostfamous kidnappers was Patty Cannon, a notoriously violent woman who, with her son-in-

law Joe Johnson, ran a tavern on the Delaware-Maryland line near the Nanticoke River.The Cannon-Johnson gang seized blacks as far north as Philadelphia and transportedthem south for sale, hiding them in her house or supposedly shackled to trees on a smallisland in the Nanticoke River, and then transporting across the Woodland ferry or loadingthem onto a schooner to be shipped down the Nanticoke for eventual sale in Georgia. In1829 Cannon and Johnson were arrested and charged with kidnapping, and Cannon wascharged with several murders, including the murder of a slave buyer for his money.Johnson was flogged, and Cannon died in jail before trial, reportedly a suicide by poison.Her skull is kept in a hatbox at the Dover Public Library. It does not circulate via inter-library loan.

For free blacks in Delaware, freedom was quite restricted. Blacks could not vote,or testify in court against whites. After Nat Turner’s 1831 rebellion in Virginia triggeredrumors and panic about a black insurrection in Sussex County, the Delaware legislature banned blacks from owning weapons, or meeting in groups larger than twelve.



Through the first half of the 19 th century the Mason-Dixon Line represented theline of freedom for tens of thousands of blacks escaping slavery in the south. TheUnderground Railroad provided food and temporary shelter at secret way-stations, andguided or sometimes transported northbound slaves across the Line. The spirituals sung by these slaves included coded references for escapees: the song “Follow the drinking

gourd” referred to the Big Dipper from which runaways could sight the North Star; theRiver Jordan was the Mason-Dixon Line; Pennsylvania was the Promised Land. After the Fugitive Slave Act of 1850 allowed slave owners to pursue their escaped slaves intothe north, the line of freedom became the Canadian border, “Canaan” in the spirituals,and abolitionists created Underground Railroad stops all the way to Canada.

Thomas Garrett, a member of Wilmington’s Quaker community, was one of themost prominent conductors on the Underground Railroad. In 1813, while Garrett wasstill living in Upper Darby, Pennsylvania, a free black employee of his family’s was

kidnapped and taken into Maryland. Garrett succeeded in rescuing her, but theexperience reportedly made him a committed abolitionist, and he dedicated the next fiftyyears of his life to helping others escape slavery.

Garrett moved to Wilmington in 1822 and lived at 227 Shipley Street, where heran a successful iron business. He befriended and helped Harriet Tubman as she broughtgroup after group of escaping slaves over the line; his house was the final step tofreedom. Garrett was caught in 1848, prosecuted and convicted, forthrightly telling thecourt he had helped over 1,400 slaves escape. Judge Roger Taney ordered Garrett to

reimburse the owners of slaves he was known to have helped, and it bankrupted him, buthe continued in his work, assisting approximately 1,300 more slaves to freedom by 1864.Taney went on to become Chief Justice of the US Supreme Court, and wrote the majoritydecision in Dred Scott v. Sanford (1857), declaring that no blacks, slave or free, couldever be US citizens, and striking down the Missouri Compromise.

In the buildup to the Civil War, Delaware was a microcosm of the country,sharply split between abolitionists in New Castle County and pro-slavery interests inSussex County. A series of abolition bills were defeated in the state legislature by a

single vote. Like other Union border states, Delaware remained a slave state during thewar, although its slave population had fallen to only a few hundred. President AbrahamLincoln offered a federal reimbursement of $500 per slave (far more than their marketvalue) to Delaware slave-owners if Delaware would abolish slavery, but the statelegislature stubbornly refused.



Lincoln’s January 1st 1863 Emancipation Proclamation abolished slavery in theConfederate states, but not in the Union border states. After the Civil War, Maryland,Pennsylvania, West Virginia, Ohio, Indiana, Illinois, Missouri and Arkansas outlawedslavery on or before their individual ratifications of the Thirteenth Amendment in 1865. New Jersey had technically abolished slavery in 1846, although it only ratified the

Amendment in 1866. So as the Thirteenth Amendment neared ratification by 27 of the36 states on December 6th 1865, America’s last two remaining slave states were Kentuckyand Delaware. Delaware didn’t ratify the Thirteenth, Fourteenth or Fifteenthamendments until 1901.

In the middle of the 20th century the Mason-Dixon Line was the backdrop for oneof the five school desegregation cases that were eventually consolidated into the USSupreme Court’s Brown v. Board of Education of Topeka case. Until 1952, publiceducation in Delaware was strictly segregated. Since the late 19th century, property taxes

paid by whites in Delaware had funded whites-only schools, while property taxes paid by blacks funded blacks-only schools. In the 1910’s, P.S. duPont had financed theconstruction of schools for black children throughout Delaware, and effectively shamedthe Legislature into providing better school facilities for whites as well. There was onlyhigh school for black children in the entire state—Howard High School. Persistentincome disparities between blacks and whites insured persistent inequalities in publiceducation.

In 1950 the Bulah family had a vegetable stand at the corner of Valley Road and

Limestone Road, and Shirley Bulah attended Hockessin Colored Elementary School 107,which had no bus service. The bus to Hockessin School 29, the white school, went right past the Bulah farm, and the Bulahs merely asked if Shirley could ride the bus to her ownschool. But Delaware law prohibited black and white children on the same school bus.

Shirley’s mother Sarah Bulah contacted Wilmington lawyer Louis Redding, whohad recently won the Parker v. University of Delaware case forcing the University toadmit blacks. In 1950, the Wilmington chapter of the NAACP had launched an effort toget black parents in and around Wilmington to register their children in white schools,

but the children were turned away. Redding chose the Bulahs as plaintiffs in one of twotest cases, and convinced Sarah Bulah to sue in Delaware’s Chancery Court for Shirley’sright to attend the white school ( Bulah v. Gebhart ). Parents of eight black children fromClaymont filed a parallel suit ( Belton v. Gebhart ). The complaints argued that the schoolsystem violated the “separate but equal” clause in Delaware’s Constitution (taken from Plessy v. Ferguson) because the white and black schools clearly were not equal.



Redding knew that a court venue on the Mason-Dixon Line, with its local legaciesof slavery and abolitionism, would be most likely to support integration. He argued thecases pro bono and the Wilmington NAACP paid the court costs. In 1952, Judge CollinsSeitz found that the plaintiffs’ black schools were not equal to the white schools, andordered the white schools to admit the plaintiff children. The Bulah v. Gebhart decision

did not challenge the “separate but equal” doctrine directly, but it was the first time anAmerican court found racial segregation in public schools to be unconstitutional. Thestate appealed Seitz’s decision to the Delaware Supreme Court, where it was upheld. Thestate’s appeal to the US Supreme Court was consolidated into the Brown v. Board case,which also upheld the decision.

The town of Milford, Delaware, had riots when it integrated its schoolsimmediately after the Brown decision. Elsewhere in Delaware, school integration proceeded slowly; the resistance to it was passive but pervasive. A decade after Brown,

Delaware still had seventeen blacks-only school districts. As Wilmington’s schools wereintegrated, upscale families, both black and white, were moving to the suburbs, leaving behind high-poverty, black-majority city neighborhoods. Wilmington’s public schoolsystem, now serving a predominantly black, low-income population, was mired incorruption and failure.

Following a second round of civil rights litigation in the 1970’s, the US ThirdCircuit court imposed a desegregation plan on New Castle County in 1976, under whichschools in Wilmington would teach grades 4, 5 and 6 for all children in the northern half

of the county, while suburban schools would teach grades 1-3 and 7-12. Wilmingtonchildren would have nine years of busing to the suburbs; suburban children would havethree years of busing to Wilmington. After the 1976 desegregation order, a spate of new private schools popped up in the suburbs. One third of all schoolchildren living withinfour districts around Wilmington now attend non-public schools.

In 1978 the Delaware legislature split the northern half of New Castle County intofour large suburban districts, each to include a slice of Wilmington. The Brandywine,Red Clay Consolidated and Colonial districts are contiguous to Wilmington and serve

adjacent city neighborhoods. The Christina district has two non-contiguous areas: thelarge Newark-Bear-Glasgow area and a high-poverty section of Wilmington about 10miles distant on I-95.

In 1995, the federal court lifted the desegregation order, declaring that the countyhad achieved “unitary status.” Wilmington’s poorest communities remain predominantly



black, but the urbanized Newark-New Castle corridor now has far more minorityhouseholds than Wilmington. The school districts are committed to reducing black-whiteschool achievement gaps as mandated under the federal No Child Left Behind Act (the2000 reauthorization of the Elementary and Secondary Education Act).

Louis Redding and Collins Seitz both died in 1998. The city government buildingat 800 North French St. in Wilmington is named in Redding’s honor.

Miscellany

The 800-acre triangular area known as the Wedge lies below the eastern end of Mason and Dixon’s West line, bounded by Mason and Dixon’s North line on the westand the 12-mile arc on the east. It is located west of Wedgewood Road, and is intersected by Rt. 896 in Delaware just before the road crosses the very northeast tip of Marylandinto Pennsylvania. Although the Delaware legislature had representatives from theWedge in the mid-19th century, jurisdiction over the Wedge remained ambiguous. A jointDelaware-Pennsylvania commission assigned it to Delaware in 1889, and Pennsylvaniaratified the assignment in 1897, but Delaware, sensitive to Wedge residents whoconsidered themselves Pennsylvanians, didn’t vote accept the Wedge as part of Delawareuntil 1921. Congress ratified the compact in 1921. Through most of the 19th century theWedge was a popular hideout for criminals, and a place for duels, prize-fighting,

gambling and other recreations, conveniently outside any official jurisdiction. A historicmarker on Rt. 896 summarizes its history. An 1849 stone marker replaced the stoneMason and Dixon used to mark the intersection of the North line with the West line;when the Wedge was annexed to Delaware in 1921 this became the MD/PA/DE tri-statemarker.

Until fairly recently, the area around Rising Sun, Maryland, had sporadic activityfrom a local Ku Klux Klan group whose occasional requests for parade permits attracteda lot of media attention. In his book Walkin’ the Line, William Ecenbarger recounts

watching a Klan rally in Rising Sun 1995. Local Klan leader Chester Doles served a prison sentence for assault, and then left Cecil County for Georgia. Whatever Klan is leftin this area has been very quiet since.

The Mason-Dixon Trail is a 193-mile hiking trail, marked in light blue paint blazes. It begins at the intersection of Pennsylvania Route 1 and the Brandywine River in



Chadds Ford, PA; runs southeast through Hockessin and Newark, DE; eastward thoughElkton to Perryville and Havre de Grace, MD (although pedestrians are not allowed onthe Rt. 40 bridge!); then northward up the west side of the Susquehanna into York County, PA, and proceeding northwest through York County through Gifford PinchotState Park to connect with the Appalachian Trail at Whiskey Springs. The Mason-Dixon

Trail does not actually follow any line that Mason and Dixon surveyed, but it’s aninteresting trail over diverse terrain.

Some of the stone markers used in the Mason-Dixon survey (Figure 10) are still in place today. The ordinary mile markers placed by the survey party are inscribed with "M"and "P" on opposite sides facing Maryland and Pennsylvania respectively. Every fifthmile was marked with a crownstone with the Calvert and Penn coats of arms on oppositesides. The locations of many of these markers are noted on USGS 7.5-minutetopographic maps, and Sandy Schenck at the Delaware Geological Survey maintains a

database of the monuments along Delaware's boundaries. . Roger Nathan and WilliamEcenbarger have both explored the Mason-Dixon survey markers and have both writtenreadable histories of them.





Figure 1: Calvert



Figure 2: Maryland “landscape” map by George Alsop (1666)



Figure 3: Penn



Figure 4: Detail from Augustine Hermann (1670) Map of Virginia and Maryland



Figure 5: Map appended to the 1732 Penn-Calvert agreement (by John Senex,1732)



Figure 6: Schematic illustration of the tangent, north and west lines.

Figure 7: John Harland farmhouse, intersection of Embreeville & Stargazer Rd.,Embreeville, PA



Figure 8: Stargazers’ Stone, Stargazer Rd., Embreeville, PA



Figure 9: Principal markers of the Mason-Dixon survey



Figure 10: Mason-Dixon mile markers



Figure 11a: Eastern portion of Mason & Dixon’s “Plan” map (1768), MD State Archives



Figure 11b: Map detail: transpeninsular, tangent and north lines



Figure 11c: Map detail, east portion of the West line



Figure 11d: Map detail, South Mountain portion of the West line,

with Pennsylvania commissioners’ signatures and seals



Figure 11e: Map detail, termination of the West line at the Great Warrior Path andDunkard Creek,

with Maryland commissioners’ signatures and seals



Bibliography (including references)

The survey journal of Mason and Dixon, written in Mason’s hand, was lost for most of a century, turning up in Halifax, Nova Scotia, in 1860; the original is now in the National Archives in Washington DC. A transcription edited by A. Hughlett Mason was published in 1969 by the American Philosophical Association. The journal is mostlytechnical notes of the survey, with letters received and comments by Mason on his travelsinterspersed. An abridged fair copy of the journal, titled “Field Notes and AstronomicalObservations of Charles Mason and Jeremiah Dixon,” is in Maryland’s Hall of Recordsin Annapolis.

Thomas Pynchon’s novel Mason & Dixon (1997) has generated a resurgence of interest in Mason and Dixon. Pynchon clearly researched the history of the survey indetail, although the book mixes in plenty of hallucination and fantasy. Mason and Dixonare portrayed as naïve, picaresque characters, the Laurel and Hardy of the 18th century,surrounded by an odd cast including a talking dog, a mechanical duck in love with aninsane French chef, an electric eel, a renegade Chinese Jesuit mercenary feng-shui

master, and a narrator who swallowed a perpetual motion watch. The two protagonists personify America’s confused moral compass, slowly realizing how their survey linedefiles a wild, innocent landscape, and opens the west to the violence and moral

ambiguities that accompany “civilization.”

In the 1940’s and 1950’s, Thomas Cope, a physics professor at the University of Pennsylvania, published a number of articles about the survey. Hubertis Cummings’s book (1962) was written for the bicentennial of the survey, and provides a good mix of technical detail and narrative. William Ecenbarger’s book (2000) describes his tour of the tangent, north and west lines, and intertwines local vignettes of slavery and civilrights with brief descriptions of the actual survey. Edwin Danson’s book (2001) providesthe clearest technical explanations of the survey along with a readable narrative of it.

Roger Nathan’s book (2000) focuses on the history of Delaware’s boundaries, in whichMason and Dixon play the largest part.

Most map scans are from the website for Maryland’s State Archives.



The Alsop (1666) map is atwww.mdarchives.state.md.us/msa/educ/exhibits/images/fig11.jpg.

The Hermann map is atwww.mdarchives.state.md.us/msa/educ/exhibits/images/fig18.jpg.

Details from the Mason-Dixon survey “Plan of the Boundaries” maps are atwww.mdarchives.state.md.us/msa/speccol/sc2200/sc2221/000017/000013/html/0000.html.

The Senex 1732 map is at www.mapsofpa.com/18thcentury/1732senex.jpg.

-------------------------------------------------------

Cope, Thomas D. 1949. Degrees along the west line, the parallel between Maryland andPennsylvania. Proceedings of the American Philosophical Society 93(2):127-133 (May1949).

Cummings, Hubertis Maurice, 1962. The Mason and Dixon line, story for a bicentenary,1763-1963. Commonwealth of Pennsylvania, Dept. of Internal Affairs, Harrisburg, PA.

Danson, Edwin, 2001 Drawing the line : How Mason and Dixon surveyed the most

famous border in America. John Wiley & Sons, New York.

Ecenbarger, William, 2000. Walkin' the line: a journey from past to present along theMason-Dixon. M. Evans, New York.

Latrobe, John H. B. 1882. The history of Mason and Dixon's line: contained in anaddress, delivered by John H. B. Latrobe of Maryland, before the Historical society of Pennsylvania, November 8, 1854. G. Bower, Oakland, DE.

http://www.mdarchives.state.md.us/msa/educ/exhibits/images/fig11.jpg


http://www.mdarchives.state.md.us/msa/speccol/sc2200/sc2221/000017/000013/html/0000.html


http://www.mapsofpa.com/18thcentury/1732senex.jpg









Mason, A.H. (ed.) Journal of Charles Mason [1728-1786] and Jeremiah Dixon [1733-1779]. 1969. Memoirs of the American Philosophical Society vol. 76). AmericanPhilosophical Society, Philadelphia.

Nathan, Roger E. 2000. East of the Mason-Dixon Line: a history of the Delaware

boundaries. Delaware Heritage Press, Wilmington, DE.

Pynchon, Thomas. 1997. Mason & Dixon. Henry Holt, New York.

Sobel, Dava. 1996. Longitude: the true story of a lone genius who solved the greatest scientific problem of his time. Walker & Co., New York.

[1] Associate Professor, Delaware Agricultural Experiment Station, University of Delaware, Newark, DE; and Member, Christina School District Board of Education, 600 North Lombard Street, Wilmington, DE. Corresponding address: [email protected] or John Mackenzie, 215 Townsend Hall, University of Delaware, Newark, DE 19717.

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a brief history of the mason-dixon survey line

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