Below are States they can't live in and why they can't.
Rhode Island -- Because Moe's Liquor licence is only good in Rhode Island
Texas -- Because no jury in the world would convict a baby... Well, maybe Texas.
Florida -- Because Florida is America's wang.
Missouri -- Springfield Elementary was voted to be the most delapatated in all of Missouri. Then moved to its current location brick by brick
Utah -- Because when Bart got caught for the Big Butt Skinner weather balloon, he wanted to race Milhouse there.
Massachusettes-- Because Homer once said "Go back to Massachusetts, you communist."
Mississippi -- In the episode when the Simpsons were visited by Sherry Bobbins, Principal Skinner was selling Jimbo on the street. Jimbo asked if it was even legal, and Skinner replied "Here, and in Mississippi."
Delaware -- "The Simpsons are going to Delaware" -- Homer
California-- There is no Springfield in California
Pennsylvania-- While talking about Pennsylvania, Homer says "Pennsylvania" it in a creepy voice.
Vermont, New Hampshire, Maine, Connecticut, New Jersey, North Carolina, South Carolina, Georgia, Illinois, Ohio, Indiana, New York, Virginia, Maryland, West Virginia, Alabama, Wisconson, Kentucky, Tennessee -- KBBL is the springfield radio station. Radio stations that begin with K are West of the Mississippi river, W are East of the Mississippi river, C are Canada, and X are Mexico. Therefore the simpsons must live in the west half of the country
Arizona -- Because Arizona smells funny
New Mexico -- "There's a NEW Mexico?" -C.M. Burns
South Dakota -- Because Mt. Rushmore is in South Dakota
North Dakota -- "North Dakota here we come!"
Arkansas, Louisianna -- In the episode where the simpsons were discussing the fact that their state flag is inappropriate, it is mentioned that they are a "Northern State"
A note to those of you who believe that the Simpsons live in Kentucky because of the "Behind the Laughter" episode: I heard that there are other versions of that episode that say a different state than Kentucky, which is why we cannot base our solution on that assertion From my calculations, the following states remain (more than half way there!):
Washington, Oregon, Nevada, Kansas, Nebraska, South Dakota, North Dakota, Minnesota, Iowa, Arkansas, and Louisianna "
After I did the research above... I found this out below...
You must realize that the simpsons reside in the continental united states. I read some people who were talking about scotland and such but that is inaccurate. In one episode they are seen being called American Haters while residing in one of the states and they make a big deal about it, so realize it is not an international answer. Two, and this is the biggest clue yet, in the episode where Bart becomes emancipated from Homer and Marge, he gets his own apartment in another section of springfield. If you will recall, Bart gets on the elevator and it goes straight up without stopping. When he gets out it is Tony Hawk's apartment. You hear Tony Hawk say that this is his place when he isnt on the road. The ironic part about this, is that Tony Hawk actually does live in a Springfield, to be more exact and are you all ready, Tony Hawk lives in Springfield, Oregon. This makes much sense with other clues because in many episodes the simpsons go to the beach and what not, which is very feasible living close to the Pacific OCean and the many lakes of the great northwest, so the answer is OREGON, there are minor things throughout the 300+episodes that can offer to contradict any answer, but that is just the creator trying to throw off all possibilities, this is the most concrete evidence to date, and pretty damm reliable, that is all for now!