Ansonia is a city and town in New Haven County, Connecticut, United States, on the Naugatuck River, immediately north of Derby and about 12 miles (19 km) northwest of New Haven. The population was 18,554 at the 2000 census. The ZIP code for Ansonia is 06401. The city has a Metro North train station, and the Route 8 state highway serves the city. Ansonia is known for its devotion to its high school football team, the Ansonia Chargers. The Chargers' arch-rivals are the Naugatuck Greyhounds, from nearby Naugatuck. The annual Ansonia-Naugatuck game is one of the most important events of the year for the two cities.