If you're a fan of South Dakota, then congratulations! You're the first person I've ever met whose actually been there. I'm not convinced it even exists, like Atlantis, Mordor, or Tulsa.
I kid though, I've actually wanted to visit for a while. In the meantime, the travel department for South Dakota is offering free “forever 605” stickers, which my basic Googling informs me is the area code for the entire state.