Suppose someone should post this... Matt's gone and done an interview where he "finally" reveals what he named Springfield after, and surprise, surprise, it's the Springfield in his home state of Oregon. Although in the same paragraph he also says he named it after Father Knows Best.
I'm sure this is shocking information to literally no one, but there you go. I'm sure he's said it before and if not, it's hardly surprising. Note how I have bolded "named" because that does not mean the same as "located" as about seven people have already decided to think it does on the Wikipedia page.