Moron Alert

This article almost made me laugh.

One would think that all other Springfields would lose out to the actual hometown of the Simpsons. And all smart people know that that is Springfield, Oregon.

And how do we know? The mountains of evidence, of course.
The creator was raised in Portland, Oregon. Most of the characters that weren't named after his immediate family were named after streets in Portland. The nuclear power plant symbolizes Weyerhauser. There are scores of references during shows...

If you look a this article, you can view Springfield, Oregon's entry which highlights the aforementioned evidence.