Animals have always played a major role in delivery services—from the Pony Express to horse-drawn carriages—but only one beast is still hauling mail today. A handful of mules still pick their way through the Grand Canyon six days a week to deliver mail and other supplies (mostly food) to the residents of Supai, Arizona. (The only other ways to reach the town are by helicopter or by rafting down the Colorado River.) The journey takes about three hours on the way down, but up to five coming back up, even after the mules have shed loads of up to 200 pounds. The Supai route was first documented in photographs in 1938, but was already well-established at that point; today, it’s the last route being serviced by mule.
Magnolia Springs, Alabama, has the only year-round water mail-delivery route in the U.S. The 31-mile-long route started back in 1915 and now services about 180 homes. (There are other water routes in the U.S., which operate on a seasonal basis.) Mailboxes are located on docks, and the delivery person drives a 15-foot Alumacraft boat that rarely comes to a complete stop.
One of those seasonal routes is Geneva Lake, Wisconsin, which employs an even more niche version of boat delivery: mail jumping, so named because the deliverer must jump off the boat onto a dock, swap incoming and outgoing mail, and jump back onto the still-moving boat. The system began in 1873, before roads had been built around the lake; these days, six jumpers are hired every year for summer delivery only.
New York, Boston, St. Louis, Chicago, and Philadelphia all used an underground system of pneumatic tubes to move mail during the early 20th century. The two-foot-long canisters held 600 letters as they moved through the tubes at an average speed of 35 mph. There were about 27 miles of pneumatic tubes running through New York City alone, including routes stretched across the Brooklyn Bridge that linked Manhattan with Brooklyn. New Yorkers, testing out the newfangled technology, sent through a Bible, a copy of the Constitution, and a cat (who emerged unharmed but presumably rattled). At its peak, nearly one third of New York mail traveled through the pneumatic system every day.
The service was suspended during WWI in an attempt to conserve funding for the war effort; after the war, only New York and Boston picked it back up again. The proliferation of delivery trucks and expanding urban centers contributed to the tubes’ demise. Private contractors leased the pneumatic tubes to the USPS, and by 1934, rates were as high as $19,000 per mile per year. Even though they’re no longer in use, many of the tubes remain intact under city streets today.
In the years following the Second World War, the volume of mail increased by more than 30 percent. Postmaster General Arthur Summerfield called for a new means of delivery to satisfy the growing demand—and thus, Missile Mail was born. On June 8, 1959, the Navy submarine USS Barbero launched a Regulus cruise missile filled with 300 commemorative letters off the coast of Florida in a demonstration-slash-publicity stunt. It was also a subtle Cold War boast; if the U.S. military was capable of such precision that missiles could be used for mail delivery, it was no stretch to think that they could also pull much less innocuous deliveries to U.S. enemies.
In late 2017, the USPS Office of the Inspector General published a white paper on how the Postal Service might incorporate autonomous vehicles into its fleet; the following spring, another white paper on mail-delivery robots followed.
Semiautonomous car tests are already under way: The USPS has partnered with the University of Michigan to develop an Autonomous Rural Delivery Vehicle, which it hopes to roll out by 2025. In the fall of 2018, Jalopnik reported that Mahindra, already in the running for the next USPS fleet contract, was also tinkering with a partially autonomous prototype. A carrier would still need to sit behind the wheel, ready to take over in case of emergency, but they could focus on sorting between stops rather than watching the road.