Batman #55

From 1949, this DC gem features a wonderfully unsettling cover by Dick Sprang and Charles Paris: the Joker looms large in the foreground, cackling into a microphone while a US map plastered with his leering face stretches behind him — forty-eight states, forty-eight Jokers. Batman and Robin swing into action on the right, racing to meet the challenge promised by the headline "Batman and Robin Battle Their Oldest Enemy State by State in 'The Case of the 48 Jokers!'" It's a snapshot of the Golden Age at its most imaginative, with the Clown Prince of Crime plotting on a genuinely national scale.