PlateHunt is the classic road trip game for finding license plates ... but on steroids. Of course, it lets you track license plates from each of the 50 US states. And beyond that, it includes Washington DC, all the Canadian provinces, US government plates, and diplomatic plates. But this is where it gets crazy. Each state produces dozens of specialty plates, including those honoring veterans, college affiliations, clubs and special causes, and various commercial and government plates. PlateHunt lets you log those too.
Have fun with the game. All I ask is that you not play the game while driving. Let a passenger do the logging. For that matter, don't text and drive, or read Facebook and drive, or basically use your smartphone while driving.