Originally posted by: nick1985
springfield is the most numerous name of a city in america. shelbyville is second. they are just screwing with you. notice in some episodes it snows, while others there is a desert. and in one episode there is a giant mountain and in the next a huge canyon. some episodes there is an ocean. face it, no state has that climate.
Oregon has that climate

And there is a Springfield in Oregon (although it doesn't have a nuclear plant) with a rival town (called Eugene).
Simpsons creator, Matt Groening, lives in Portland.
Several Simpsons characters come from Portland streets and landmarks. For example, Ned Flanders is from NE Flanders St. There's also SW Terwilliger Blvd., SW Montgomery St., Burnside St., and more.
In the actual show, though, the Springfield could be anywhere. It's fiction.