A few people living in the Grand Canyon still receive mail through mules. This is most likely one of the last official mail through mule routes in the world, according to Daniel Piazza, the patron curator of philately at the Smithsonian National Postal Museum.
Mail has been delivered by mule since 1930. Mules still carry mail to people who live in Supai, located in the Grand Canyon, outside of National Park Service jurisdiction. Supai is only accessible by hiking, taking a helicopter, rafting down the Colorado River, or by riding a mule: Mule trips take three to five hours down and back up.
Mules carry a limit of 200 pounds at a time while delivering items. This is why only one or two mules are on route every day. Mail is not the only thing being delivered by mule: food is also delivered. The majority of deliveries by mule is food, according to Piazza as a lot of people live approximately 45 minutes away from the nearest town. The U.S. Postal Service has a lot of dedication to their deliveries.
Mail through mules has many pros and cons. For example, Supai’s high temperatures can reach up to more than 90 degrees during the summer. The routes followed by mules do not have any accessibility to water thus mules can become dehydrated. On the positive side, mules do not use gas. Gas costs can range from $3 to $5, and mules save lots of money for the U.S. postal service.
[Sources: Smithsonian Institution, National Geographic]