I made this map at http://www.epgsoft.com/VisitedStatesMap/ and it really struck me as odd. Obviously I've not spent time in the Northwest but how the hell have I not been to Iowa? Maybe I have and I can't remember, but I lived in Kansas City for three years and never went that direction.
I didn't just list states that I've driven through or flown over, I only listed states that I went to a specific destination there. For example I've been to Washington State, the airport I spent two hours in was beautiful. That doesn't count, I didn't go to Washington on purpose. I counted Maine though, because I was in New Hampshire and I said "I want to go to Maine" so I crossed the state line just so I could say I've been to Maine. I really can't think of another reason to go there. Which also explains why I've never been to Iowa.