This is one of the more arcane questions I could come up with, and there's probably a better way to phrase it, but where have the vehicles you've driven been registered? (This not the same question as in which states you've driven.)
I have held a driver's license in CA, FL, IA, MA, MS, PA, and TX. I can't recall exactly, but I'd imagine that I've registered a car in all those states as well. Usually, it depends upon when my old one expires. I tend not to get a new driver's license or license plate as soon as I move, but eventually the old one expires and I have to.
I've also briefly owned cars with Arkansas Maryland, Minnesota, and Wisconsin plates, but those were on cars I bought out-of-state. I had them registered in my home state as soon as I could, usually within a week, so I don't know if they count.