When have I reasonably earned a state sticker?

My theory is if you drive through them (with an RV, I've seen a few with Hawaii?) you can claim them. Some states are fairly narrow like Tennessee. If I had to camp there, I would lose the better part of a travel day heading south.

I like the idea of getting the kids to have to spell the state, or maybe have a journal where they can write what they saw as they were in that state, then put the sticker on the map.