Southern Tier

The Southern Tier is the counties of New York State west of the Catskill Mountains along the northern border of Pennsylvania. It generally includes the counties that border Pennsylvania west of Delaware County, but definitions of the region varies widely.

The region is bordered to the south by the Northern Tier of Pennsylvania, and together these regions are known as the Twin Tiers.

Occasionally but less frequently included in the "Southern Tier" designation are Schuyler County, Chautauqua County (primarily the "South County" region in the Conewango Creek watershed; other areas are part of the Niagara Frontier), Yates County, Cortland County, Tompkins County, and (far more rarely) Schoharie County, Chenango County, and Otsego County (the last three of these, along with Broome County, are also commonly considered part of the "Central Leatherstocking Region"), however Schoharie County is also listed as part of the Capital District. At least one definition used by the state Department of Transportation includes Sullivan County, which usually isn't included in other definitions. The National Weather Service office in Buffalo occasionally includes Wyoming County and, more rarely, Southern Erie County in its definition.

The Encyclopedia of New York State lists only Chautauqua, Cattaraugus, Allegany, and Steuben Counties as part of the Southern Tier, with anything east of that being considered Central New York. Other definitions define it as comprising the combined Corning-Elmira-Binghamton Metropolitan Statistical Areas, which includes Steuben, Chemung, Tioga and Broome Counties but not Chautauqua, Cattaraugus or Allegany, which are considered Western New York.

The New York State Division of Local Government Services presently classifies the following fourteen counties as members of the Southern Tier: Allegany, Broome, Cattaraugus, Chautauqua, Chemung, Chenango, Cortland, Delaware, Otsego, Schoharie, Schuyler, Steuben, Tioga, and Tompkins. This definition corresponds to the same 14 counties in New York State that are members of the Appalachian Regional Commission formed in 1963.

In virtually all contexts, the Southern Tier is considered a part of the broader Upstate New York region.

Much of the Southern Tier is in area code 607, with the exception of Allegany and Cattaraugus Counties, which are in area code 716 or area code 585. The westernmost portion of the Southern Tier is also located in New York's 29th congressional district as of 2007; the rest is divided among New York's 24th congressional district and New York's 22nd congressional district, the last of these containing a curious gerrymander ribbon that runs through Binghamton, connecting the heavily liberal enclave of Ithaca to other like-minded areas in upstate. The ZIP code prefixes 147 (Jamestown region), 148 - 149 (Elmira region), and 137 - 139 (Binghamton region) are set aside for the Southern Tier.