NY 124 is a short north/south route extending from Pound Ridge to South Salem. It begins at the point where NY 137 curves west onto Stone Hill Road. For most of its length, it is known as Salem Road. Near the northern terminus, Salem Road ends at Spring Street, which extends both east and west to Old Post Road (NY 35). NY 124 follows the west leg, while the east leg has a reference route number of 983D.
NY 124 shares its number with CT 124, and while the two routes come within a couple of miles of each other, they don't exactly connect. At the state line, Oenoke Ridge (CT 124) turns into Westchester Avenue, a town road that merges with High Ridge Road (NY 137) in Pound Ridge, about a mile south of the southern terminus of Salem Road (NY 124). Heading south on NY 137, the turnoff for Westchester Avenue is marked as leading to Connector NY 124, even though this is not an official designation for Westchester Avenue. It is likely that the people who installed the connector sign intended for it to serve as an abbreviation for Connecticut.