For the first fifty years of City Free Delivery Service, letter carriers brought Americans’ mail directly to their door. As early as the 1880s, the postal service had begun to encourage homeowners to attach mailboxes to their houses. While some households invested in metal or glass containers to hold mail, most continued to rely on the carriers’ knock, whistle, or ring of the doorbell (yes, the postman did ring twice) to signal their mail’s arrival.
In 1916, efficiency experts determined that letter carriers lost almost two hours a day waiting for patrons to come to the door. In response, the Post Office Department declared that every household must attach a mail box or letter slot to their home in order to receive mail.