Mattoon (mătˌōnˈ) [key], city (1990 pop. 18,441), Coles co., E central Ill.; inc. 1859. It is a processing, rail, and industrial center for a farming region. Among its manufactures are paper products, electrical and fire-prevention equipment, machinery, and signs. Nearby are many oil wells, a fish hatchery, and Lake Mattoon. The farm and grave of Abraham Lincoln's father and stepmother are southeast of the city.