NY 100B begins at an intersection with NY 9A (Saw Mill River Road) in the town of Greenburgh, right next to the New York State Thruway (I-87). Known as Dobbs Ferry Road, NY 100B proceeds northeast through Greenburgh as a two-lane residential street, passing the local Ferncliff Cemetery and bending east into a junction with Park Avenue.
NY 100B commences at an intersection with NY 9A (Saw Mill River Road) in the town of Greenburgh, immediately adjacent to the New York State Thruway (I-87). Known as Dobbs Ferry Road, NY 100B heads northeast through Greenburgh along a two-lane residential street, passing by the nearby Ferncliff Cemetery and turning east into a junction with Park Avenue.