100) in Briarcliff Manor to US 9 north of Ossining. The highway, known as the Briarcliff–Peekskill Parkway, was completed and initially designated as NY 404. On January 1, 1949, NY 9A was altered to continue north along a slightly realigned Saw Mill River Road from NY 100C near Elmsford to the south end of the Briarcliff–Peekskill Parkway in Briarcliff Manor. At this point, NY 9A left Saw Mill River Road and followed the parkway to its end at US 9, supplanting NY 404. The realignment created a overlap between NY 9A and NY 100 from Hawthorne to Briarcliff Manor and resulted in the truncation of NY 141 back to its previous terminus in Hawthorne. Construction on the Croton Expressway, the only piece of the failed Hudson River Expressway project that was ever built, began in the mid-1960s. It became part of a realigned US 9 when it was completed by 1967. The former surface routing of US 9 along Albany Post Road between Croton-on-Hudson and Buchanan became a northward extension of NY 9A, which reached the old alignment by way of an overlap with US 9 from the north end of the Briarcliff–Peekskill Parkway to Croton-on-Hudson. New York City As the Henry Hudson Parkway replaced Riverside Drive in the mid-1930s, NY 9A was moved onto it, eventually using the new parkway to where it crossed US 9 (Broadway) in the Bronx. Here, NY 9A exited the parkway and ran concurrent with US 9 to the split in Yonkers. The Brooklyn–Battery Tunnel connecting Manhattan's Battery Park to Brooklyn was completed in 1950. By 1960, an extension of the West Side Elevated Highway south to the Manhattan tunnel portal became part of NY 27A, which had ended in Brooklyn prior to the construction of the tunnel. On January 1, 1970, NY 27A was truncated on its western end to eastern Nassau County while NY 27 was extended northward over NY 27A's former routing through the Battery Tunnel and the West Side Elevated Highway. However, by 1973, NY 27 had been cut back to its interchange with the Gowanus Expressway in Brooklyn while unsigned I-478 was assigned to both the Battery Tunnel and all of the West Side Elevated Highway south of the Lincoln Tunnel. NY 9A was cut back to the Lincoln Tunnel as a result. The extension of I-478 into Manhattan was eliminated following the collapse of part of the Elevated