This 1880s advertising poster has been circulating the internet; Anderson saw it on Lawyers, Guns, and Money. It’s also in the Library of Congress collection. While I’d love to have one, I kind of doubt it’s still available for 5 one cent stamps (somewhere on the poster it makes that offer). Anderson also found one reference to Mississippi as the Tadpole State (“The average white man of the Tadpole State has always been more or less crazy, and he is not responsible for anything he does.”) in a weekly from Seattle, although an 1879 source I found uses the term in a more generic sense (“Why will Greeley persist in going to that tadpole State of Indiana to give his agricultural addresses ?”). A book called Labels for Locals: What to Call People from Abeline to Zimbabwe lists these nicknames for Mississippi: “Traditional personal nicknames: Border Eagle, Mud Cat, Mud Waddler, and Tadpole State.”
I’ll leave it to folks from Missouri to show me why they might be the Puke State on this map.