Beginning at a point on State Highway Route Number Two Hundred and Fifty-seven Between Moon Run and North Star in Allegheny County; and thence running northwesterly in the direction of Imperial and Clinton to a point on the dividing line between Allegheny and Beaver Counties; and thence continuing northwesterly in the direction of Harshaville to a point on State Highway Route Number Two Hundred and Seventy-eight in the vicinity of Laughlin's Corners; and thence continuing westerly or northwesterly to a point on the dividing-line between the State of Pennsylvania and the State of West Virginia.
36 P.S. § 1512