Any land surveyor who has established property lines created by sequential conveyances has most likely encountered gaps and overlaps between adjoining properties. Typically, the problem was caused by one or more ambiguous legal descriptions – different points of beginning or contradictory controlling calls within the conveyances. Depending on the relationship between the adjoiners, the problem can either be resolved amicably or by adjudication. In some instances, as in the case of the boundary dispute between Maryland and Pennsylvania, the dispute escalates to violence.

In 1632, King Charles I granted the “Maryland colony” to Cecilus Calvert, “Baron of Baltemore.” The compensation being that two “Indian Arrowes” be delivered to the castle every year on the Tuesday of Easter week and also “the fifth part of all gold and silver ore.”

Problematic Legal Description

Some 49 years later, King Charles II granted the “Pennsylvania Colony” to William Penn. Unlike the Maryland colony, portions of Penn’s land had been previously inhabited by Europeans. Both the Swedish and Dutch had built military settlements in the area where he developed his first city: Philadelphia.

The north boundary of the Maryland Colony was described in the Royal Charter as:

“…unto that part of Delaware Bay on the North, which lieth under the fortieth degree of Northerly Latitude from the Equinoctiall, where New England ends…”

The south boundary of the Pennsylvania Colony was described as:

“…all that tract...bounded on the south, by a circle drawne at twelve miles, distance from New Castle Northwards, and Westwards unto the beginning of the fortieth degree of Northerne Latitude; and then by a straight line Westwards, to the limit of Longitude above menconed.”

There was a problem: a 12-mile radius circle around New Castle doesn’t mathematically intersect the 40th parallel.  

Furthermore, Pennsylvania officials called into question how a “beginning of latitude” was defined. They contended that a degree of latitude was “some certain divisible space, having not only a beginning…but a termination.” Thus, the line labeled as 40 degrees north on a map is actually the termination. The “beginning” of the latitude would be the line labeled as 39 degrees. Understandably, Maryland disagreed with this interpretation, since it would have shifted their northerly boundary 69 miles south and essentially cut their colony in half.

Enter the Surveyors

By 1684, both colonies were aware of the problem and had sent their own surveyors into the overlapping territory.  Penn couldn’t come to an agreement with the local governors of the Maryland colony, so he returned to England in order to meet with the Calverts and resolve the problem. But, 15 years later, he returned to Pennsylvania, still without an official solution to the border problem. The issue remained unresolved at the time of his death in 1718. 

By the late 1720s, the disputed area between Maryland and Pennsylvania still wasn’t resolved, but it had been narrowed down to roughly a 20-mile strip of land lying southerly of the 40th degree of latitude and westerly of the Susquehanna River.  

Immigration to colonial America wasn’t isolated to British gentry or Englishmen wanting to better their station in life. There were a number of German, Irish, and Scotch-Irish immigrants living along the Susquehanna River and claiming Pennsylvania citizenship at the time.

According to Charles Dutrizac, “Wherever the authority of the [Maryland and Pennsylvania] colonies overlapped, a shrewd settler stood to gain, although the risks were high. If he could avoid being drawn directly into conflict and was willing to live with less security, he could take advantage of cheap land prices and the postponement of quitrent payments to enhance his position in society.”

Cresap’s Role

Around 1729, nearly a century after the Maryland land grant, Thomas Cresap enters into the story. Little is known about his early life, but it appears that he journeyed alone to the Maryland Colony from Yorkshire, England at approximately the age of 15. 

Cresap, along with others, were issued patents from Maryland to farm land in the disputed territory. Their neighbors on the east side of the Susquehanna River were John Wright, a Pennsylvania magistrate and ferry owner, and James Patterson, an “Indian trader” licensed by the Pennsylvania colony.

Patterson deemed the Marylanders to be squatters and routinely let his horses wander through their farms and graze on their crops. Cresap and his family responded by killing his horses.

Cresap’s other formidable neighbor, John Wright, operated the only ferry service available to cross the Susquehanna River. Cresap decided to build his own ferry a few miles north of it and was issued a patent from the Maryland authorities to do so. One day, after picking up three Pennsylvanians, Cresap and his “man,” Chance, were attacked about 70 yards from the east bank of the river while transporting the passengers across the Susquehanna. Cresap was thrown into the river, his “flat” stolen and Chance captured.

Cresap survived and, after recovering from the attack, sought the Justice of Lancaster County, Pa., in order to issue a warrant for the three men. He also charged that his Pennsylvania neighbors had offered a reward to anyone who would burn his house down and drive him and his family south.

According to Cresap, the Justice “made sport” of him and told him that he “could not expect any favors in Lancaster County” since he was operating a ferry illegally without a Pennsylvania license 12 miles north of the border of Maryland. Accordingly, Lancaster County officially disavowed the attack and said that the “Irish of Lancaster County were acting without authority in harassing him.”

Attempted Boundary Agreement

After this incident and other outbursts of violence in 1732, the Maryland and Pennsylvania governors came together and entered into a boundary agreement. They accepted the boundary between the colonies to be a line about 15 miles south of Philadelphia. However, this agreement didn’t seem to mean much to the settlers or local authorities, as it was generally ignored.

In 1735, the violence and animosity between the colonies was at its peak. After being denied land patents by Pennsylvania, a number of settlers crossed the Susquehanna River into the disputed area, claimed Maryland citizenship and began homesteading. Two of these settlers were Andrew Magill and Jacob Loughman.  

It was important to each colony to have more settlers than the other, so they could essentially claim squatter’s rights. After hearing of Magill and Loughman’s change of allegiance, Robert Buchanan, the sheriff of Lancaster County (Pa.), crossed the river with warrants for the men.

Buchannan and his posse found Magill working with a Marylander named Joseph Ogle. According to Ogle, Buchannan’s men tore down their fences, trampled the corn and assaulted Magill. When Ogle intervened, they showed him a Pennsylvania writ for a tax debt. Ogle informed them that Magill had paid taxes to Maryland, so he shouldn’t be bound by Pennsylvania law and suggested that Buchannan see the Maryland authority. Since Thomas Cresap was the Maryland authority at the time, Buchanan declined and took Ogle to a Pennsylvania jail cell instead.

The next day, Buchanan went after Loughman. The posse found the German settler at his home and asked him to accompany them across the river, in order to pay a debt to two Philadelphia merchants. He informed them that the debt had been paid and refused to go. After his wife intervened and Buchanan and his men whipped her, he consented. When Loughman asked them why the suit wasn’t filed in a Maryland court, he claimed that he was beaten and that Buchanan told him that he wouldn’t be allowed bail.

As the Pennsylvanians were escorting their prisoner back to Lancaster County, they met Robert Evans on the road.  Evans was a former Pennsylvanian, who was now a Maryland peace officer and a man in good standing with the German settlers in the region.  

When he was informed of the reason for the arrest, Evans told him that they would post his bail and that Loughman should be released. By this time, a number of German settlers had arrived on the scene, and when Buchanan refused to release his prisoner, the scene became heated. One of the Pennsylvania men struck a German bystander and a brawl erupted. The result of the melee was that Loughman was freed, and the Marylanders captured Buchannan and his men and marched them to Annapolis, Md.

Shortly after this incident, Loughman, Evans and the other German settlers in the disputed area decided to reclaim Pennsylvania citizenship. The reason for the shift of allegiance is unknown, but some sources indicate that they tired of Cresap’s bullying ways. Others contend that they were simply offered a better deal by Pennsylvania.  

Regardless of the reason, Maryland authorities were worried about losing numbers in the disputed area, so they enlisted a large group of Scotch-Irish men to oust the Pennsylvania German settlers and hold their land as Marylanders.

Pennsylvania authorities got wind of the ploy prior to the attacks, but they had their own concern. Since their militia was essentially comprised of Scotch-Irish men as well, they feared that their forces wouldn’t fight against their countrymen.

Petitioning the King

The magistrate of Lancaster County believed that if he could remove Thomas Cresap from the disputed area, the rest of the Marylanders would leave. Acting on his own accord, the magistrate sent his sheriff and a group of 20 armed men across the Susquehanna River.

After surrounding Cresap’s home, they demanded that he surrender. As an answer, Cresap shot one of them in the leg. After refusing multiple requests to exit the home, the sheriff and his men set fire to it. Cresap was captured and taken to Lancaster County.

After receiving news of the arrest, Lord Baltimore petitioned the king directly for a resolution to the boundary dispute. On Aug. 18, 1737, the main violence in the disputed area ended when the king expressly forbade “all disorders along the boundaries, also enjoining them from making grants in the disputed territory.” The boundary agreed upon back in 1732 was officially held as the border between the colonies.

After a mob ran off a survey party commissioned by the Calverts of Maryland in 1743, the “Court of Chancery” established a bipartisan commission to survey and monument the boundary between the colonies. In 1750, local surveyors were hired; however, they lacked the equipment and skill to establish the line on the ground, so the commission turned to two British surveyors named Charles Mason and Jeremiah Dixon

Click here to learn more about the history of surveying.

In the spring of 1764, they commenced their survey. It was officially completed in 1768, when 200 copies of the survey were presented to their commissioners. Nearly 84 years after the overlap between the colonies was discovered, it was now officially resolved in what is perhaps the most famous survey in U.S. history.


  1. “Europe Meets America: Property Rights in the New World” by Andrew Morriss dated Jan. 1, 2007
  2. “History of the United States” by Charles A. Goodrich, published 1823
  3. “Cresap’s War: the Lancaster County border struggle” by Henry Eshleman, published 1909
  4. “Lecture upon the controversy between Pennsylvania and Virginia, about the boundary line” by Craig, Neville B. published 1843
  5. “A brief history of the Mason-Dixon Line” by John Mackenzie