The state chartered Ansonia as a borough of Derby in 1864, and later as a separate town in 1889. In 1893, Ansonia incorporated as a city, consolidating with the boundaries of the town.
The state chartered Ansonia as a borough under Derby in 1864 and later granted it autonomy as a separate town in 1889. In 1893, Ansonia became a city by merging its territory with the existing town's boundaries.