The Simpsons Movie

You can go vote for Springfield, Missouri to be the Springfield of the Simpsons, just go to http://www.usatoday.com/life/movies/simpsons-contest.htm

There is alot of evidence that Missouri is the home of the Simpsons.

In various episodes of the Simpsons referenced a radio station: KBBL-CA, LPTV station in Springfield, Missouri

The Wacking Day episode would commerate Springfield, Missouri's history, when coberas got loose from a circus or something and were hunted down, I think it was back in the 50s, anyway, I learned that at the History Musume at the City Hall.

From Wikipedia i found: In this episode it is revealed that the school was called the worst school in Missouri, supposedly revealing which state Springfield is in, causing Lisa and Principal Skinner to react in astonishment at the fact that the location has been revealed, but immediately afterward it is said that the school was moved "brick by brick" to its current, still unknown, location. This does, however, indicate that Springfield is not in Missouri.

(In the first run of the 'Behind the laughter' episode it is stated that the Simpsons are a "northern Kentucky family." However in re-runs of this episode it is stated that they are a "Southern Missouri" family. Either way there are many hints throughout the shows run to suggest that Springfield is somewhere in the Southern or Midwestern United States. )-Trivia Section of IMDB.com