New York State Route 426 (NY 426) is a state highway located entirely within Chautauqua County, New York, in the United States. It runs just over from one section of the Pennsylvania state line to another, passing through two small hamlets and providing the Southern Tier Expressway (Interstate 86 or I-86 and NY 17) with its westernmost exit in New York. NY 426 is the westernmost north–south state highway in New York.