Interstate 86 (Pennsylvania–New York)

Interstate 86 (I-86) is an Interstate Highway that extends for 254.02 miles (408.81 km) through northwestern Pennsylvania and the Southern Tier region of New York, in the United States. The highway has two segments: the longer of the two begins at an interchange with I-90 east of Erie, Pennsylvania, and ends at New York State Route 26 (NY 26) in Vestal, New York in Broome County, while the second extends from I-81 east of Binghamton to NY 79 in Windsor. When projects to upgrade the existing NY 17 to Interstate Highway standards are completed, I-86 will extend from I-90 near Erie to the New York State Thruway (I-87) in Woodbury. The portion in Erie County, Pennsylvania, is known as the Hopkins-Bowser Highway and is signed as such at each end. In New York, the current and future alignment of I-86 is known as the Southern Tier Expressway west of I-81 in Binghamton and the Quickway east of I-81.

I-86 travels 7.00 miles (11.27 km) in Pennsylvania and 247.02 miles (397.54 km) in New York. Except for a section of about 1.5 miles (2.4 km) that dips into Pennsylvania at exit 60 near the New York village of Waverly, the Pennsylvania borough of South Waverly, and the section passing through Greenfield Township from I-90 to the Pennsylvania/New York Border, the rest of I-86 will be in New York. The section of NY 17 through South Waverly is maintained by the New York State Department of Transportation (NYSDOT), however. The Southern Tier Expressway section of I-86 and NY 17 comprises Corridor T of the Appalachian Development Highway System. I-86 connects to US Route 219 (US 219) in Salamanca, Seneca Nation; I-390 near Avoca and I-99/US 15 just west of Corning.

Most of the Quickway and the Southern Tier Expressway was built in stages from the 1950s to the 1980s. The I-86 designation was assigned on December 3, 1999, to the entirety of since-decommissioned Pennsylvania Route 17 (PA 17) and to the westernmost 177 miles (285 km) of NY 17. It has been extended eastward as more sections of the existing NY 17 freeway have been upgraded to Interstate Highway standards, first to NY 14 in Horseheads in 2004, to NY 352 in Elmira in 2008, and its current terminus at the Chemung–Tioga county line in 2013. The segment of NY 17 between I-81 and NY 79 was designated as part of I-86 in 2006, but this segment currently remains discontinuous with the rest of I-86 while work is being done in the Binghamton area to bring NY 17 up to Interstate standards.