The postcard of the men on the dock was printed in Germany but mailed from Lake Huntington, New York with a message about doing one's best to keep the lake from running dry.  Ten days later, with a note about the usefulness of a handful of grass, the same person mailed the second card, which was made IN  Lake Harrington, to the same recipient.  Both cards actually went through the mail (postmarked, though the stamps have since been stolen) and remain as lasting proof of, well, something or other.