The first rural mailboxes were odds and ends. At that time, rural mailboxes appeared in almost every shape and size imaginable. People used any container they could find: empty coal oil or syrup can, an apple, soap, or sugar box, a lard pail hung on a fence post. Such homemade containers were often the wrong size for the mail and placed in a variety of heights. Many were difficult to open or close and some even held remnants of oil or syrup which came off on the letters. Frustrated rural carriers and local postmasters appealed to the Post Office Department to impose certain requirements for rural mailboxes.
In 1901 postal officials asked manufacturers to design a mailbox that could become a standard for the service. Among their requirements for the design was a box that was made of metal, 6” x 8” x 18” in size, weather proof, and easy to fasten to a post. Hundreds of designs deluged postal headquarters, with only a few acceptable to the Department. By the next year, the Department required customers to have these boxes. Unfortunately, not all postal patrons purchased the suggested boxes. Many simply made their own, which as one mailbox advertisement observed, were "better fitted for rat traps or puzzles for the insane."
The familiar tunnel-box design that continues to hold rural mail to this day was designed by Roy Joroleman, a Post Office Department engineer. The box included a signal flag that was attached to the mailbox, which the carrier raised once the mail had been placed inside. Customers also raised the signal flag when they placed outgoing mail in the mailbox to make sure the carrier would stop. The signal was appreciated by all, especially on frosty or stormy days.