- Western Terminus:
- Pennsylvania-New York state line
- Eastern Terminus:
- Southern Tier Expressway (NY 17/Future I-86) and US 220 at the New York-Pennsylvania state line
- 205.25 miles
- Chautauqua, Cattaraugus, Allegany, Steuben, Chemung, Tioga
The Southern Tier Expressway is a major highway in Western New York. It is the southernmost east/west highway in this region of the state, running just north of the border with Pennsylvania. It begins at I-90 in North East, Pennsylvania, and enters New York after a few miles. It runs through the area south of the Finger Lakes to end at I-81 in Syracuse.
The Southern Tier Expressway was originally built as NY 17. Work is in progress to upgrade it to interstate standards, at which time the entire length will be designated I-86. The Quickway, which carries the NY 17 designation from I-81 in Syracuse to the New York Thruway (I-87) in Harriman, will also be designated I-86 once it has been fully upgraded. At this point, the work has progressed to a point where the I-86 designation has been applied first 205 miles from where the Southern Tier Expressway first enters New York to exit 60 at US 220, where it dips south of the border back into Pennsylvania for a short distance. I-86 is multiplexed with NY 17 for its entire length in New York.