NY 308 was designated as part of the 1930 renumbering of New York state highways, incorporating a portion of the former Ulster and Delaware Turnpike. The route originally extended from Milan westward to Rhinecliff to serve a ferry landing on the Hudson River. It was truncated to US 9 in the 1960s, but its former routing to Rhinecliff is still state-maintained as an unsigned reference route. The highway was also intended to cross the Hudson via the Kingston–Rhinecliff Bridge until plans were changed to involve other routes and the site for the bridge was moved about upriver.