The Springfield Effect is the name given to an alleged phenomenon by which every place named Springfield is supposedly hard-linked in hyperspace to every other place of this name, according to some Discordians, subGenii, and other surrealistically inclined mystics. This is given as an explanation for the reason why there are more cities in the United States by that name than any other - including some cases where more than one exists in a single state - and why they all allegedly look the same.
The Effect was first propounded publicly by Andrew C. Bulhak, Lt Wilkes, and Schol-R-LEA;2 on the alt.discordia USENET group 1994. It is alleged that cartoonist Matt Groening was aware of it even earlier, and that the stories for the cartoon series The Simpsons includes clues to this. Similarly, it is sometimes held that the Men In Black have long used the city as a base of operations.
According to this claim, the city of Springfield has some very peculiar properties. It is described as existing outside of normal reality, in a sort of hyperspace. Because it connects to many different locales world wide, it supposedly can be used to rapidly travel between far-flung locations. However, the hyperspacial nature of the city is said to cloud the minds of ordinary individuals, with the result that they can only see the 'local' Springfield they believe themselves to be in; only mystical adepts of the 'theochaotic' sects where this theory is prevalent can navigate through the city successfully. According to some claims, certain landmarks - including a vast, looming, nuclear power plant, and a cross-dimensional highway named 'Metaworld 95' - can be readily identified regardless of where one enters the city. Supposedly, M-95 connects Springfield to two other interdimensional cities, known as Tanelorn and Cynosure; it is said to be impossible to travel between the two other cities without passing through Springfield at least once.
Needless to say, it is generally assumed that this is nothing more than an elaborate surrealist joke, but when asked about it, most Discordians assert that it must be the literal truth because it is an elaborate surrealist joke.
Text blatantly ripped off of TVWiki