NY 12F begins at an intersection with
NY 180 south of the village of
Dexter in the town of
Hounsfield. The route heads to the east, following the southern bank of the
Black River through undeveloped areas of
Jefferson County. One exception to this lies midway between Dexter and
Brownville, however, as NY 12F passes by
Watertown International Airport, located in an otherwise barren area south of the highway. East of the airport, the route proceeds to the southern outskirts of Brownville, where it connects to Bridge Street, a connector linking NY 12F to
NY 12E on the opposite side of the river in Brownville. The connector is designated as
NY 971H, an unsigned
reference route. Past Bridge Street, NY 12E becomes the riverside highway—albeit on the northern bank—while NY 12F turns southeast to follow a linear routing into the
town of Watertown. Within Watertown, NY 12F passes a mixture of commercial and residential areas overlooking the Black River, which rejoins NY 12F several blocks into the city limits. NY 12F and the river enter downtown Watertown soon afterward, where NY 12F ends at a junction with
US 11 and
NY 12 just northwest of the city's central business district. ==History==