- Southern Terminus:
- Boston Post Road (US 1) in Rye
- Northern Terminus:
- Saw Mill River Road (NY 100) in Millwood
- 18.03 miles
NY 120 is a north/south route in Westchester County. The first section is Purchase Street, which begins at Boston Post Road (US 1) in Rye. It runs north through Purchase, where it has interchanges with the Cross Westchester Expressway (I-287) and the Hutchinson Parkway, to Armonk. There, it comes very close to the border with Connecticut and has an interchange with I-684 near Westchester County Airport. Purchase Street ends at King Street (NY 120A) a block away from the state line. NY 120 continue north along King Street to Chappaqua and then follows Quaker Street until it ends at Millwood Road (NY 133). NY 120 is multiplexed with NY 133 to Millwood, where NY 133 splits off onto Station Place. NY 120 continues along Millwood Road for another two blocks, after which it ends at Saw Mill River Road (NY 100).