New York State Route 21 (NY 21) is a state highway extending for about through the western part of New York in the United States. The southern terminus of the route is at an intersection with NY 417 in the village of Andover, and its northern terminus is at a junction with NY 104 in the town of Williamson. In between, NY 21 serves the cities of Hornell and Canandaigua and intersects several major east–west routes, including the Southern Tier Expressway (I-86/NY 17) near Hornell, the conjoined routes of U.S. Route 20 (US 20) and NY 5 in Canandaigua, the New York State Thruway (I-90) in Manchester, and NY 31 in Palmyra. NY 21 originally extended from the Pennsylvania state line in the south to Lake Ontario in the north when it was assigned as part of the 1930 renumbering of state highways in New York. South of Hornell, the route followed modern NY 36. NY 21 was rerouted to follow its current alignment south of Hornell in the 1950s and truncated on its northern end to Williamson in 1980. Other changes of local importance, mostly realignments to bypass communities along the route, have also occurred at various points in the route's history. NY 21 originally had an alternate route around Canandaigua Lake; however, that highway—designated NY 21A—was eliminated in the 1940s. Route description Andover to Naples NY 21 begins at an intersection with NY 417 in the village of Andover. The route heads northward, paralleling the Western New York and Pennsylvania Railroad (WNYP) through a rural stretch of eastern Allegany County. At Alfred Station, located just east of the village of Alfred, the highway meets the eastern terminus of NY 244. NY 21 and the WNYP head northeast through the village of Almond to the Steuben County line, where the road and rail line begin to turn to the southeast toward Hornell. The portion of NY 21 near Almond briefly parallels the Southern Tier Expressway, designated Interstate 86 (I-86) and NY 17. East of the county line, NY 21 leaves the vicinity of the expressway and passes through another undeveloped stretch to reach the city of Hornell, where it becomes West Main Street. The highway follows West Main Street for several blocks into the city's downtown district, where it crosses the Norfolk Southern Railway's Southern Tier Line and intersects NY 36. NY 21 turns north onto NY 36, separating