The United States Postal Service has a new stamp series that recreates WPA posters. One of them says Visit the Zoo. I showed parts of the surrounding stamps on the sheet, but edited it so the zoo one is brighter.
WPA stands for Works Progress Administration. This was a public works program to provide government jobs during the Great Depression of the 1930's. The posters were done not only to celebrate the many public facilities that benefit but also to provide work for artists who created them. Many zoos benefitted from new cages and infrastructure as a result of the WPA.
The subheading WPA POSTERS is the name of the series and the FOREVER refers to the fact that you can use this stamp for first class mail indefinitely. A few years ago the US Postal Service made a very welcome change where they stopped putting the monetary value on first class stamps and simply put forever. Now when stamp prices increase, as a random example from 42 cents to 44 cents, you no longer have to buy a two cent stamp to add to your old stamp.