Answer: Smokey Bear
There are many hard-working public service mascots: Woodsy Owl, McGruff the Crime Dog, and Eddie Eagle, to name just a few. None of these mascots are so popular that they deserve their own zip code for mail delivery, with the exception of the Smokey Bear "Only you can prevent forest fires" (the slogan was updated in April 2001
What Smokey Did to It The kind of fame truck truckloads brought to Fanpost was the US Forest Service's decision to adopt a real bear as a mascot. In 1950, firefighters rescued an American black bear cub from a massive wildfire in the Capitan Mountains of New Mexico, and the Forest Service adopted it as the living embodiment of Smokey Bear. The bear cub turned out to be so popular with children across the country that the forest service received stacks of fan mail. In fact, so much fan mail that the US Postal Service Smokey assigned its own zip code in 1964 to simplify the sorting of fan mail bags. This postcode is for Curious 20252 (which is still used).
Smokey the Bear lived the remaining 26 years of his life at the National Zoo and was buried at the Smokey Bear Historic Park in Capitan, New Mexico after his death. The Smokey Bear character remains the most popular public announcement mascot in US history, and licensing his image earns millions of dollars each year to fund fire prevention efforts.