Tri-State Marker Trail

The Tri-State Marker Trail leads to one of the most historically significant and geographically unusual spots in the mid-Atlantic region: the tripoint where the borders of Delaware, Pennsylvania, and Maryland converge at a single point on the ground, marked by a stone monument erected during the colonial-era boundary survey. The precise location was determined by Mason and Dixon during their famous 1763-1767 survey commissioned to resolve boundary disputes among the Penn and Calvert proprietorships, and the original survey marks — some still visible in the landscape — represent one of the most important achievements of 18th century American surveying and mathematics. The trail follows White Clay Creek upstream on a gentle gradient through floodplain forest to a side trail junction, then climbs a short ridge to reach the clearing where the tripoint monument stands. The monument itself is a modest stone marker, but its location draws visitors from all three states who enjoy the novelty of standing simultaneously in Delaware, Pennsylvania, and Maryland. The surrounding forest is a transition zone between piedmont woodland types characteristic of each state, making the botanical composition itself a sort of natural boundary marker. The creek crossing near the tripoint provides an opportunity to observe crayfish, stonefly larvae, and water pennies in the clear, rocky shallows. The White Clay Creek Preserve in Pennsylvania is accessible across the state line, extending hiking opportunities significantly into Chester County.