NY 171 is the only signed state highway in New York that does not intersect any other signed New York state routes. However, this was not always the case. When it was originally assigned as part of the 1930 renumbering of state highways in New York, Main Street in Frankfort was part of NY 5S. A new freeway alignment for NY 5S was constructed between Utica and Ilion in the late 1960s, isolating NY 171 from the remainder of the state highway system. Frankfort's interchange with NY 5S is now at Cemetery Street, to the west.