Ansonia is a city in New Haven County, Connecticut, United States, on the Naugatuck River, immediately north of Derby, and about northwest of New Haven. The population was 19,249 at the 2010 census. The ZIP code for Ansonia is 06401. The city is served by the Metro-North Railroad. Ansonia Station is a stop on the railroad passenger commuter service's Waterbury Branch connecting to New York's Grand Central Terminal. Ansonia also is served by the Connecticut Transit bus carrier. Connecticut Route 8 serves Ansonia (Northbound, Exit 18; Southbound, Exit 19).