Across the county line in the town of Mendon, NY 15A takes on the name Rush–Lima Road and begins curving to the northwest. It connects to Honeoye Falls twice: first via Main Street at a junction just north of the county line, and later by way of Monroe Street (formerly NY 363) at an intersection to the northwest. Past Monroe Street, the route makes a long, significant turn to the west, following Honeoye Creek into the town of Rush and the hamlet of the same name. The highway meets Rush–West Rush Road at an intersection south of the community, at which point NY 15A turns back to the north and crosses over Honeoye Creek. In the process, NY 15A becomes East Henrietta Road, a name the highway retains until its northern end in Rochester. On the opposite side of the creek, NY 15A intersects NY 251 in the center of Rush.