The exact date of the first settlement near the current site of Canonsburg is unclear. Colonel John Canon, a common miller who also served as justice of the Virginia courts at Fort Dunmore (better known as Fort Pitt, now Pittsburgh), purchased some land from the state of Virginia around Chartiers Creek, sometime before May 1780. The state had claimed what is now southwestern Pennsylvania in a dispute that would not finally be settled until later in the decade. In 1781 Pennsylvania carved Washington County out of Westmoreland County, and the county seat was established at Washington. The notes of the first session of the Washington County Court during that year indicate a call for a road from Canon's mill to Pittsburgh. The road to Pittsburgh, called Pitt Street, remains in part today as an archaic and indirect route to the city. The first surviving plat of the town is from April 15, 1788. Lots were sold around Canon's property, and the emerging town took the name of Canonsburg shortly thereafter.