Streator (strēˈtər) [key], city (1990 pop. 14,121), La Salle and Livingston counties, N central Ill., on the Vermillion River; inc. 1882. It is an industrial center with diverse manufactures. Coal, discovered in the early 1860s, was the principal source of livelihood until the deposits were exhausted (c.1900). Several state parks are in the area.