NY 427 was extended northward along Pennsylvania Avenue to a new terminus at Water Street (NY 14 and NY 17E; later NY 352) as part of the change. At the other end of the route, the easternmost part of NY 427 was realigned  to follow Wyncoop Creek Road to a new interchange (exit 59) with the Southern Tier Expressway (NY 17) in Chemung.
The route NY 427 was extended northward along Pennsylvania Avenue, reaching a new terminus at Water Street (later NY 352). At the eastern end of the route, NY 427's path was realigned to follow Wyncoop Creek Road and connect with an interchange (exit 59) on the Southern Tier Expressway (NY 17) in Chemung.