NY 100 then branches off on its own again in Briarcliff Manor, with NY 9A continuing north along the Briarcliff–Peekskill Parkway and NY 100 continuing northeast on the Saw Mill River Road, which roughly follows New York Central's old Putnam Division railroad. Many of the railroad's old stations can still be found along the highway. NY 100 passes through New Castle and meets NY 133 in the hamlet of Millwood, where access to the Taconic State Parkway can also be made. From here, NY 100 then follows the path of the Croton Turnpike (alternatively known in the area as Somerstown Turnpike and also as Saw Mill River Road). The road continues into the town of Yorktown, passing by the hamlet of Kitchawan. NY 100 then crosses the Croton Reservoir on Pines Bridge. After crossing the reservoir, NY 118 splits off to the west on Saw Mill River Road, while NY 100 continues northeast on the Croton Turnpike.