New York–Pennsylvania border

It has three sections: The survey of the 42nd parallel north was carried out in 1785–86 and accepted by the two states in 1787.

The surveying technique that was used at the time was not especially accurate, and as such, this boundary wanders a bit on both sides of the true parallel.

The survey of the Erie Triangle boundary in 1789 was by the top surveyor in the United States of the time, Andrew Ellicott.

The starting point of the 42nd parallel north line is in the Delaware River at the northeast corner of Wayne County, Pennsylvania at 41°59′57″ N, 75°21′35″ W WGS 84.

The initial surveyor's monument is just west of Faulkner Road at 41°59′58″ N, 75°21′43″ W. The corner point of the Erie Triangle in modern coordinates is 41°59′55″ N, 79°45′43″ W. The distance along the east–west line is approximately 225.86 miles (363.49 km).

Tri-States Monument , where New York , New Jersey , and Pennsylvania meet. In the background, Interstate 84 crosses between NY and PA just north of the monument.
Monument along the 42nd parallel where the state line leaves the West Branch of the Delaware and runs along land
The cornerstone of the Erie Triangle—the westernmost point in the state of New York