WOW! Nice total! Has your kid been to all those states too? If so, that's a great experience to get as a kid!
I used to have a job where I travelled a lot all over the place. When my neice and nephew were little, I bought them a big map of the world, and would send them postcards from wherever I was. They would look at the card and then get to find the place on the map, and at least have a little taste of the rest of the world.
I'v been to 42. Missing Nevada, Nebraska, the Dakotas, Minnesota, Rhode Island, Iowa and Wisconsin. Between ski racing, 3 cross country drives by myself taking different routes each time and various travel with family I've hit most.

- CO to be added Feb.