NY 48 begins at I-690 exit 3 just west of the Geddes town line in Van Buren, Onondaga County. Known as State Fair Boulevard, it proceeds west-northwest, paralleling both NY 690 (the northward continuation of I-690) and the Seneca River as it passes south of the Seneca Golf Club and Community Park. Shortly after passing the park, NY 48 enters the village of Baldwinsville on Syracuse Street and intersects Downer Street, the former routing of NY 31 west of the village. Originally, NY 31 overlapped NY 48 across the Seneca River (here part of the Erie Canal) to Genesee Street; now, however, NY 48 continues alone to Genesee, where it intersects the modern routing of NY 31 (concurrent with NY 370) through Baldwinsville. North of NY 31 and NY 370, NY 48 becomes Oswego Street and turns northwest before traveling south of Lysander Park as it exits the village and becomes Oswego Road.