Waterbury, city, coextensive with the town (township) of Waterbury, New Haven county, west-central Connecticut, U.S., on the Naugatuck River. Mattatuck Plantation, settled in 1674 as part of Farmington, was incorporated (1686) as the town of Waterbury, so named because of the abundant drainage of the locality. The city, incorporated in 1853, was consolidated with the town in 1902. In the 19th century industrialization stimulated the growth of Waterbury, which became the nation’s largest producer of brass products. Other manufactures included clocks and watches (made and marketed with great success by Robert H. Ingersoll), buttons, and pewter. Teikyo Post University (1890), Naugatuck Valley Community-Technical College (1964), and an extension of the University of Connecticut are in the city. Pop. (2010) 110,366; (2020) 114,403.