Postcards, when you still see them in shops today, seem mostly relegated to pleasing vacationers who’ve yet to master sending photos in a text. But postcards were once a creative medium that went beyond just tourist-attraction photos; they also delved into humor, not unlike our still surviving greeting-card industry. They were an easy way to let someone know you were thinking of them, sharing a long-distance gag. My favorites are the unexpectedly off-color joke cards from the turn of the century.