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 starts at an intersection with NY 9A (Saw Mill River Road) in Greenburgh, right next to the New York State Thruway (I-87). Known as Dobbs Ferry Road, NY 100B travels northeast through Greenburgh on a two-lane residential street, passing Ferncliff Cemetery and eventually merging with Park Avenue.