I found this neat tool on World66, a Travel info site.  It allows you to create a map of states and countries you’ve visited.  You can find the tool here, and click to the left to see what states I’ve visited.  I’ve been to 21 states, which is 41%  of the states out there, not counting some that I’ve simply driven through.   I count "visited" as having actually experienced something there… had a meal, spent a night or two, visited friends, done something "local" etc.