Twin Tiers

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.

The Twin Tiers are the collective counties that lie on the New York–Pennsylvania border on either side of the 42nd parallel north. The region is predominantly rural and contains many small towns.

Separately, the two halves of the Twin Tiers region are known as the Southern Tier region in the state of New York and the Northern Tier region in the Commonwealth of Pennsylvania. The "Northern" and "Southern" designations are relative to the states in which they are located, not relative to each other.