it's intentionally kept a secret, so that they can place it in a variety of environments (the city has snow covered mountains, deserts, and hurricanes). i do remember at one point they said it was in ohio, but in the form of a joke or something (i haven't watched the show in years; i don't remember exactly how it went). i suppose they may have decided on a location for it since i stopped watching, but i doubt it.
Homer has to go to the Springfield hall of records to clear up a report of his death. He tells the clerk that the stone angel visible in the cemetery is his mother's head stone. When he goes to look at the actual name on the stone it turns out to be Walt Whitman and not his mother's name. Walt Whitman is Buried in Camden New Jersey. Just a stones throw from Springfield New jersey. They live in Evergreen Terrese! http://wiki.answers.com/Q/What_state_do_the_Simpsons_live_in
watch the movie... it'll tell you. i forget exactly what it says in the movie.. but it's something like they live right on the border of oregon, new mexico, kentucky, and ohio.
Yeah, it was something ridiculous like that, they threw Nevada in there as well. So it can pretty much be anywhere. Ghost Lyric's answer is interesting.
the creator, matt groening grew up in oregon... i think portland.. he named a lot of things in the simpson from places and people he knew/knows.
all interesting answers, but has been mentioned, they did say in one episode that they're from "oh heya o... mod"
Yeah i have always been satisfied leaving it at Ohio, but really, there probably are elements of other states in the mythical simspsons springfield. So think we are all right
i think there really isnt a state. and theyre just trying to fuck with ppl to try to figure it out. after all, its been on forever... the mystery helps.
Actually, that was an interesting read for a simpsons fan such as myself. I was a bit offended by the petition though