 NY 393 was assigned in the early 1930s as a signed designation for a highway that the state of New York had assumed maintenance of in the 1910s. It originally extended west along Mitchell Street to NY 79, but was truncated to Ithaca Road when NY 13 was rerouted through Ithaca in the mid-1930s. The NY 393 designation was removed in the mid-1960s, and its former routing is now maintained by the city of Ithaca and Tompkins County. The designation is currently reserved by the New York State Department of Transportation for a highway in Chautauqua County.
