NY 9X began at the intersection of West 207th Street and Broadway (US 9) in the Manhattan neighborhood of Inwood.

The route headed to the southeast, following 207th Street for five blocks through Inwood prior to crossing over the Harlem River on the University Heights Bridge.

On the opposite side of the river in the Bronx, within the community of University Heights, NY 9X became Fordham Road and continued east to a junction with Sedgwick Avenue.

While Fordham Road continued on to meet US 1, located just three blocks to the east, NY 9X turned north to follow Sedgwick Avenue along the Harlem River.

NY 9X ended at this point, located just 1 mile (1.6 km) northeast of where the route began in Inwood.