Unknowable Episode 33: National Park Disappearances

Did you know that the actual number of people who have gone missing in national parks and public land in the United States is unknown? There is no database to keep track of such a thing, and yet some estimate that the number is in the thousands, some of those people disappearing -- or reappearing -- in bizarre ways. Is this merely an example of disorganization within our government? Or is there something more sinister afoot?