Didn't you get the memo? It's a mythical place subject to much debate as to whether or not it existed once upon a time, much like Atlantis. Only instead of sinking into the ocean, rumor has it Iowa sank into the Great Plains, or was possibly swallowed up by a temporal hellmouth and disappeared from our reality. Some schools of thought even believe that there's evidence of Iowa resurfacing in Middle Earth, but most academics think this little subgroup of believers are crackershit insane.
Edit, sorry: The actual quote is here by kuchenhexe