Pony Express mochila

A mochila (Spanish, pronounced [mo-chee-lah], for "knapsack", "pack", "pouch") is a removable lightweight leather cover put over a horse's saddle. In the nineteenth century, it was used as a mail bag by the Pony Express. The eighth-of-an-inch leather cover draped over the saddle on a horse. There were slits cut into the leather which allowed the saddle horn and cantle to protrude through.

Riders of the Pony Express made quick exchanges to new fresh horses, usually within a few minutes at each remount station on their route across the United States. The mochila was removed from the exhausted horse and swiftly placed over the saddle of the new fresh waiting horse that the relay station had for him.

Joan Corominas derives the Spanish mochila from mochil ("delivery boy"), itself from Basque mutil ("boy").

The word "mochila" connotes the soft sheepskin leather.

Saddle bag mail pouches were never in use on the Pony Express system because of their unwieldiness. The normal large saddle bags were not adept to attaching to a saddle efficiently and would cause much delay when going from an exhausted horse to a fresh horse when the Pony Express rider switched horses at a station. In 1860 the Pony Express developed a fast mail delivery system using a special saddle mail bag cover called a mochila that made the Pony Express unique. The cover, which had 4 hard leather boxes to carry the mail, was quick and efficient when transferring from one horse to another. All the rider had to do was change this leather cover with the mail boxes over to a ready horse waiting for him at the station, which was usually done in under 2 minutes. If a horse was injured on the way from one station to another and not capable of further traveling, then all a rider had to do was to take the cover with its mail off the injured horse and walk to the next station to get a new horse. He then threw the cover onto the new saddled horse. The leather blanket cover was designed by Jay G. Kelley, another Pony Express rider. The saddles for the horses that traveled over the Overland Pony Express route were special and standardized, built by a saddlery firm owned and franchised by Israel Landis and sons.

Pony Express riders traveled about 100 miles at any one time. In this travel they would change horses every dozen or so miles. When he changed horses to a fresh new horse the rider would grab the mochila off the saddle of the exhausted horse and throw it over the saddle of the new horse at a remount station. This mochila saddle blanket cover the rider would then sit on. It had sewn to it certain pockets that were always locked. Only authorized people could unlock these attached pockets to retrieve the mail. This mail service was very expensive (e.g., 1–5 dollars per half ounce, an astronomical amount that only businesses could afford).

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