NY 173 was assigned as part of the 1930 renumbering of state highways in New York to its modern alignment. The route itself has not been altered since; however, the portion of the route from Onondaga to Manlius became part of NY 20N and a small section of the route within Manlius was included in NY 20SY when that highway was assigned in the early 1950s. Both designations were removed in 1961. All of NY 173 east of Onondaga was originally part of the Seneca Turnpike.