Whistle for letter carriers
City letter carrier Louis Wharton Weissert used this mustard-colored, plastic whistle to signal his arrival on a patron’s doorstep.
Prior to 1916 the postman really did ring twice or blew a whistle or knocked. Letter carriers waited for someone to answer the signal. If no one responded, they took the mail back to the post office and tried again the next day. Studies have shown that carriers spent an average of two hours daily waiting at the doorstep. To save work hours, the Post Office Department required residents to install mailboxes or letter slots in 1923.