Railway Post Office (RPO) & Railway Mail Service

RPO car interiors, which at first consisted of solid wood furniture and fixtures, would also soon be redesigned. In 1879, an RMS employee named Charles R. Harrison developed a new set of fixtures that soon gained widespread use. Harrison's design consisted of hinged, cast-iron fixtures that could be unfolded and set up in a number of configurations to hold mail pouches, racks and a sorting table as needed for specific routes. The fixtures were also designed so they could be folded away completely to provide a wholly open space to carry general baggage and express shipments as needed by the railroads. 

The July 1, 1862, Pacific Railroad Act signed by President Lincoln established government funding for the construction of a railroad from the Missouri River to the Pacific Ocean with the express idea of opening a main line mail route across the western frontier. The act was officially entitled "AN ACT to aid in the construction of a railroad and telegraph line from the Missouri river to the Pacific Ocean, and to secure to the government the use of the same for postal, military, and other purposes," The Act opened the door to government funded railroad mail routes across the American continent.

By the 1880s, railway post office routes were operating on the vast majority of passenger trains in the United States. A complex network of interconnected routes allowed mail to be transported and delivered in a remarkably short time.

Railway mail clerks were subjected to stringent training and ongoing testing of details regarding their handling of the mail. On a given RPO route, each clerk was expected to know not only the post offices and rail junctions along the route, but also specific local delivery details within each of the larger cities served by the route.

Because of the physical and mental demands placed on RPO clerks, the Railway Mail Service pushed the adoption of standardized floor plans and fixtures for all RPO cars, with the first plans published in 1885. The RMS also pressed for improved lighting fixtures to help the clerks see the addresses on the mail they sorted. Clerks' safety was also of great concern to the RMS, with the first comprehensive statistics on work-related injuries published in 1877.

As the development of passenger cars progressed, so too did the development of RPO cars. The first plans for RPO car designs were based on light baggage car frames and bodies. In 1912, the Railway Mail Service developed a set of strength requirements for new cars in an effort to push the car building companies into using steel for the cars' major structural components and underframes.

An interesting feature of most RPO cars was a hook that could be used to snatch a leather or canvas pouch of outgoing mail hanging on a track-side mail crane at smaller towns where the train did not stop. 

With the train often operating at 70 mph or more, a postal clerk would have a pouch of mail ready to be dispatched as the train passed the station. In a co-ordinated movement, the catcher arm was swung out to catch the hanging mail pouch while the clerk stood in the open doorway. The mail pouch had a strap around the middle, and the strap was tightened in preparation for pickup with an approximately equivalent weight of mail in either end of the pouch to prevent the heavier end from pulling the lighter end off the catcher arm. As the inbound pouch slammed into the catcher arm, the clerk kicked the outbound mail pouch out of the car, making certain to kick it far enough that it was not sucked back under the train. 

Outbound pouches of first class mail were sealed with a locked strap for security. Larger sacks with optional provisions for locking were used for newspapers, magazines, and parcel post. An employee of the local post office would retrieve the pouches and sacks and deliver them to the post office.

Most RPO cars had a mail slot on the side of the car, so that mail could actually be deposited in the car, much like using the corner mailbox, while the train was stopped at a station. Those desiring the fastest delivery would bring their letters to the train station for dispatch on the RPO, knowing that overnight delivery would be virtually assured. 

The mail handled in this manner received a cancellation just as if it had been mailed at a local post office, with the cancel giving the train number, endpoint cities of the RPO route, the date, and RMS Railway Mail Service killer bars. At their height, RPO cars were used on over 9,000 train routes covering more than 200,000 route miles in North America. While the majority of this service consisted of one or more cars at the head end of passenger trains, many railways operated solid mail trains between major cities; these solid mail trains would often carry 300 tons of mail daily.