Springfield is the city where the Simpson family live. It is located near Shelbyville and Capital City in a state whose name is never mentioned. The evidence is sufficiently contradictory that it cannot be identified with a specific state. Its population is estimated to be about 30,720. It is known as a twin city to Shelbyville.

Founded in 1796 by Jebediah Springfield, and a band of fiercely determined pioneers out of Maryland who set off after misinterpreting a passage in the bible, Springfield seems to be a small city rather than a megalopolis. Its features include one nuclear power plant; two elementary schools; a minor league baseball stadium; an airport; a harbor; a downtown district; a large tire fire yard; a ghetto; a Russian district; its own Little Italy; several specialized shopping districts, Moe's; and Barney's Bowl-A-Rama.

Springfield's nearest neighboring town is Shelbyville. There is a strong rivalry between the towns, dating back to a rivalry between their founders — Jebediah Springfield and Shelbyville Manhattan. Manhattan wanted to found a city where men were free to marry their cousins, but Springfield refused to allow it, so Shelbyville was founded as a rival town.