I was talking to someone today and he said he was from California, so I asked where in Cali. He said, "I'm from Humboldt County", and kept going, assuming I knew all about it. When I said I hadn't heard of it before, he said, "I didn't think there was an American alive who hadn't heard of Humboldt County!"
So I looked it up on Wikipedia, and didn't see any obvious signs that all Americans should know about this county:
Maybe I'm crazy though. Have you ever heard of Humboldt County?