A dispute having arisen as to the correct division line between the heirs of William Penn the proprietor of Pennsylvania, and those of Lord Baltimore, the proprietor of Maryland, two eminent surveyors from London, Charles Mason and Jeremiah Dixon were sent out to establish the line between the two colonies in the summer of 1763.
After various calculations and astronomical observations they determined the starting point on the Delaware river, and thence with a circular line to the point where the States of Pennsylvania, Delaware and Maryland now join and from thence ran the division line westward.
The work was slowly continued from year to year until in 1767 the surveyors reached a point near Mount Morris, now in Greene County, Pennsylvania, where they were ordered to stop by the Indians, and work was not resumed again in the field for seventeen years.
The intention of the commissioners was, after passing the Western limit of Maryland, to find the western boundary of Pennsylvania, five degrees of longitude from the Delaware River.
As long as the territory of the western country was a wilderness no attention was given to the boundary line between Pennsylvania and Virginia, but when settlers began to locate in the country a bitter controversy arose as to what authority would exercise jurisdiction over the country.
Augusta County, Virginia, claimed that South West Pennsylvania, including the site of Fort Pitt was in her boundary, which claim was denied by the latter colony.
In the year 1774 Lord Dunmore, the Royal Governor of Virginia, directed a county court to be held for Augusta County at Port Pitt, and the first Court was actually held there in February 1775 and proceeded to exercise jurisdiction over the surrounding settlements.
This was vigorously resisted by the Pennsylvania authorities and resulted in there being two sets of laws and two sets of officials to enforce them.
The Virginia officers arrested and imprisoned the Pennsylvania officers and the latter retaliated by doing likewise, and so intense did the controversy become that a resort to arms was imminent.
But the breaking out of the war of the Revolution caused an end to the dispute and all parties agreed to sink their local differences and unite in a patriotic cause against the common enemy.
When the war was drawing to a close and the two colonies had been elevated to the dignity of independent states it was amicably agreed that the Mason and Dixon line should be extended to the West.
Commissioners were appointed and after many delays caused by hostile Indians, lack of rations and other difficulties incident to the wilderness, the long contest was at last satisfactorily adjusted as will be shown by tie following official agreement:
"Agreement of Commissioners for Southern and Western Boundary of Pennsylvania.
Baltimore, 31st. August 1779.
We, James Madison and Robert Andrews, commissioners for the State of Virginia and George Bryan, John Ewing and David Rittenhouse, commissioners for the State of Pennsylvania, do hereby mutually in behalf of our respective states ratify and confirm the following agreement, viz.: To extend Mason's and Dixon's line due West five degrees of longitude to be computed from the River Delaware for the Southern boundary of Pennsylvania, and that a meridian drawn from the Western extremity thereof to the northern limit of the said state be the western boundary of Pennsylvania forever.
In witness whereof we have hereunto set our hands this thirty first day of August in the year of our Lord 1779.
|James Madison,||George Bryan,|
|Robert Andrews.||John Ewing,|
Pursuant to this agreement the commissioners of the two States assembled in 1784 at the point which the survey had been discontinued and extended the line to the termination of the said five degrees of longitude from the Delaware river, which marked the Southern boundary of the State of Pennsylvania.
The line was marked by cutting a vista through the forest and at intervals planting posts marked with the letters P and V, each letter facing the State of which it was the initial. At the extremity of the line which was the South West Corner of Pennsylvania; a square unlettered White Oak Post was planted around whose base there was raised a pile of stones.
The advanced season of the year forced the commission to suspend operations until the following spring. The report of their operations is dated in Washington County, Pennsylvania, November 18, 1784 and is signed by John Ewing, David Rittenhouse, Thomas Hutchins, Robert Andrews and Andrew Ellicott
The following year 1785 the commissioners met at the South West corner of Pennsylvania and ran the line due North to the Ohio River thus establishing the line between Pennsylvania and the Pan Handle Counties of Virginia.
This boundary line between the states mentioned took the name of the two original surveyors, Mason and Dixon, and in after years became famous in the political history of the country, as being the dividing line between the free and slave states.