Bedrock, Colorado is the only town of that name in the US and as a result their tiny post office receives all the fan mail addressed to “The Flintstones.” They have a special stamp for rejecting the mail that says: “Return to Sender – Fictitious Cartoon Character.” – WTF Fun Facts
Source: https://www.telluridenews.com/news/article_192d67ed-26a2-5928-8ff4-dd2d59ed6ea7.html