- Southern Terminus:
- FDR Drive and Hugh L. Carey Tunnel (I-478) in Manhattan
- Northern Terminus:
- Briarcliff-Peekskill Parkway (US 9) in Peekskill
- 47.25 miles
- New York, Bronx, Westchester
NY 9A begins at the Battery in Manhattan. The southern section was originally a limited-access highway called the West Side Highway. This highway collapsed, and NY 9A was rerouted along West Street, 11 Avenue, and 12 Avenue. This section is a large two-way divided boulevard with traffic lights that runs along the West Side of Manhattan. It has certain intersections signed as exits with exit numbers. Further north in Manhattan, NY 9A becomes the Henry Hudson Parkway, a limited-access highway for noncommercial vehicles only. It runs north through Manhattan past the George Washington Bridge (I-95). At the northern end of Manhattan, the Henry Hudson Parkway crosses the Harlem River to the Bronx on the Henry Hudson Bridge. It continues north through the Bronx.
Near the Bronx-Westchester county line, NY 9A splits off from the Henry Hudson Parkway and is multiplexed with US 9 along Broadway. Slightly north of the Bronx-Westchester county line, NY 9A splits off from US 9 and runs east along Ashburton Avenue for a short distance. It is then routed north through Westchester along Saw Mill River Road and the Briarcliff-Peekskill Parkway to US 9 in Ossining. It is multiplexed with US 9 along the Croton Expressway for a short distance. It splits off and runs along South Riverside Avenue, North Riverside Avenue, and Albany Post Road, the former route of US 9 prior to the construction of the Croton Expressway. It ends at the Croton Expressway (US 9) in Peekskill.