Twin Tiers

The Twin Tiers are the collective counties that lie on the New York–Pennsylvania border on either side of the 42nd parallel north.

The Twin Tiers region is usually defined as including these counties: McKean, Potter, and (less often) Cameron Counties refer to themselves as part of the Twin Tiers, but almost never consider themselves part of the Northern Tier, instead going by the name "Northern Pennsylvania".

Significant ambiguity often exists in regions: for instance, the western part of the region (McKean and Potter Counties) often associate themselves with St. Marys, a city larger than any city in that area, but in Elk County, just south of what is considered "Northern Tier" by any standard.

The region was historically a disputed territory in the history of the United States prior to its founding.

The region's name originated in 1968 as part of a marketing campaign in the Elmira Star-Gazette that used twins.

This map indicates the area known as the Twin Tiers. Counties in **dark green** are almost always considered part of the Southern Tier . Counties in **dark red** indicate the Northern Tier . Counties in **blue** are those in Pennsylvania that use the name "Northern Pennsylvania," and counties in **light green** are those that sometimes consider themselves Southern Tier counties. The **light blue** areas are associated with the Twin Tiers but are not part of the region proper.