I’m pretty sure the writers are systematically eliminating every state they can. I just roll with it…
Hey, no, wait! If the state is fictional, it must be Delaware, the non-existent state!!
Wait…no, there was a rerun last week where they tried to book a trip TO Delaware. Damn.
In the episode Kill the Gator and Run, at the end the family is looking at a map of the US for vacation spots. Every state except two - South Dakota and Arizona - has been eliminated because the family has been kicked out of it. Homer refuses to go to Arizona (“Arizona smells”), leaving North Dakota the only state left. And they don’t LIVE there, they’re going to visit it.
In the episode “Mr. Lisa Goes to Washington,” in which Lisa wins a trip from “Reading Digest,” there is a shot panning over the U.S. Map. There is a big star with the word “Springfield” on the map, implying that this is Springield’s state. The star is in one of the states which comprise Four Corners, the only point in America where four states meet. I forget which state it’s in, but I am certain of my facts. NO, this does not refer to “Five Corners,” a fictional place mentioned in at least one other episode.
It’s a pointless argument about a cartoon show, but I have decided that this is the final answer, at least in my mind…
hrh
**(hijack) **
RealityChuck, leave your theory, as Joseph his coat in the hand of the harlot, and flee!
–Hobgoblins of Springfield Association
Yes, but that state had the initials “NT” on them. There is no state with “NT” for initials.
Obligatory www.snpp.com reference
There are a lot of fictional references in “The Simpsons.” 
NT stands for “Not Telling.”
hrh
And if anyone wants to tell me what the heck happened with my link, I’d be much obliged!
There was one episode where Homer discovered what he thought was his mothers grave was actually Walt Whitman’s, so that would place it in New Jersey. In another Hank Hill stated he had travelled 2,000 miles to see a football game in Springfield.
Great air conditioners.
Just to add to the confusion there was a hurricane which would place it in either on the East Coast or the South.
Actually it is located in Las Vegas. There was a home developer here that ran a promotion that you could win the Simpsons house. They had a house built, and painted just like the one they live in. After awhile they held the raffle and anounced the results during a Simpsons episode. Only problem is that once the promotion was over the house was painted back to “normal” colors.
Any theory you come up with is slightly hampered by the fact that “West Springfield” is several times larger than Texas.
Matt Groenig is from the suburbs of Portland, Oregon, and I strongly suspect that he had suburban Portland in mind when he created the Simpsons.
However, as others have noted, there’s no way to pinpoint exactly where Springfield is, because the writers change the terrain and layout of the city from week to week, to suit their needs. If they need a scene by the ocean, Springfield will have an ocean. If they need a scene in the desert, behold! Springfield will have a desert.
Springfield is infinitely malleable, since it’s not a real place. It’s whatever and wherever the writers need it to be.
This is actually true, at least in a way. Many of the characters are named for streets in Portland. I remember Kearney is one, I think Lovejoy was another. There’s also a Northeast Flanders street … NE Flanders … it was often changed to “Ned Flanders” by vandals.
[Hijack/Nitpick] Actually, the fictional state is Wyoming. When a cartographer was making a map of the U.S., he found a missing spot, so he just wrote Wyoming (An old episode of “Garfield & Friends”).[/Hijack/Nitpick]
Moving this to Shelbyville…err…Cafe Society.
I always thought it was in Ohio. Of course, I could be wrong.
That or Indiana (I think).
Well given that Paris is actually in Texas, and that Texas is in Queensland, Australia (it is! Look it up!) and that the state of Queensland is about 3 times the size of Texas, well I think we have our answer, don’t you?
Sorry, Boo Boo Foo. You’re too far east.
It’s been mentioned many times above that Springfield is in a state abbreviated as NT.
Northern Territory.
Ever wondered why they have that big red rock in their back yard?
I guess I’m not very observational. What red rock in the back yard?
Book me a flight to the state that Springfield is in!
Actually, figuring this out should be quite simple. Just find a state where the people are yellow, have three fingers, and are two dimensional. How many can there be?