Something silly: Here is a map of States I've visited:
create your own visited states map
or check out these Google Hacks.
I've driven through RI, and I've passed through KS and NM by train. However, I still counted them in (because I spent quite a bit of time doing so, or as much as possible in the case of RI).
I've also changed planes in MN, and passed through a corner of IA by train at night, but I didn't count them (because the time spent was pretty short).
All the rest I've visited or made at least one stop. Apparently, Wisconsin is the only State east of the Mississippi River I have yet to visit.