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By 1730 violence had broken out between Pennsylvania and Maryland colonists over conflicting border claims. On May 10, 1732, Charles Calvert (1699–1751), Fifth Lord Baltimore and proprietary governor of Maryland, established a provisional agreement with William Penn’s sons, John (1700–46), Thomas (1702–75) and Richard Sr. (1706–71), proprietors of Pennsylvania, to survey their mutual border. At the time, the agreement also seemed to settle the dispute between the proprietors regarding the ownership of the three Lower Counties (today’s Delaware), which had been a point of contention between the two families since 1681. Settlers of this contested area had refused to pay for lands with indefinite titles until the boundary was finally determined, costing both the Penns and Calvert significant income.

In the same year that the 1732 Articles of Agreement had been signed, however, Calvert reneged on the pact. He raised several objections to the work of the commissioners who had been appointed to supervise the surveying, including the agreement’s map engraved at John Senex’s shop. The joint commissioners admitted failure in November 1733, having been unable to come to an agreement on the radius of the New Castle circle. Calvert then claimed that the agreement was void.

In 1735 the Penns brought suit against Calvert in the English Court of Chancery for breach and nonperformance of the 1732 Articles of Agreement and the costs and expenses associated with it. Calvert obtained a 10-month delay by asserting that the Penns’ bill against him was both scandalous and impertinent, and he later further accused them of deceiving him with a forged map that they knew to be dreadfully inaccurate. As the case moved very slowly through the British judicial system, riots and skirmishes continued to erupt between Maryland and Pennsylvania settlers.

Finally, Lord High Chancellor Philip Yorke of Great Britain heard the case of the Penns against Calvert in May 1750. Yorke sided with the Penns and ruled that the Articles of Agreement were “valid and obligatory upon the several parties who executed the same.” He further ordered that the agreement be carried into execution and that Calvert was responsible for paying the expenses of the lawsuit and the Penns’ costs related to the initial commissioners of 1732–33.

In 1751 Charles Calvert died and the proprietorship of Maryland passed to his son Frederick Calvert (1731–71), Sixth Lord Baltimore, who argued that he should not be bound by the agreement that his father had made with the Penns. Again the surveying of the border was delayed for an additional 10 years. Eventually, Frederick Calvert did agree to abide by the 1750 decree in exchange for the Penns releasing his obligation to pay their litigation costs. A new legal document was deemed necessary for refining and implementing the Articles of Agreement of 1732. Pictured here, that document known as the “Penn-Baltimore Agreement,” dated July 4, 1760, is an indenture of agreement between the proprietors to terms from which a scientific survey could take place to finalize the border between Pennsylvania, Maryland and the three Lower Counties.

Attempts were undertaken to establish the boundary between 1761 and 1762, but they failed, as the hired surveyors quarreled and the commissioners disagreed over a variety of issues. Inadequate equipment and the surveyors’ lack of skill also hindered the efforts. In June 1763 the Penns and Calvert agreed to hire English surveyors Charles Mason and Jeremiah Dixon to establish the boundary between the two proprietary colonies that had been in dispute for more than 80 years. This set the stage for Mason and Dixon to take over the survey in the fall of 1763 and complete it in late 1767 (see “‘Restless Progress in America’: Drawing the Mason-Dixon Line”).

The Penn-Baltimore Agreement was referred to in the 1853 published Pennsylvania Archives as “the foundation of the famous Mason & Dixon’s Line.” The original document is held at the Pennsylvania State Archives in Record Group 26, Department of State.


Richard C. Saylor is an archivist for the Pennsylvania State Archives and author of the award-winning book Soldiers to Governors and numerous articles on military, political and sports history.