For much of postal history, mail was sorted by hand using the “pigeon-hole box” method. Addresses were read and manually slotted into specific compartments. While early forms of a mechanical mail sorter were developed and tested in the 1920s, the first high functioning sorting machine were put into operation in the 1950s. To handle rapidly growing mail volumes, the Post Office Department installed the first semi-automatic sorting machine on April 10, 1957. The letter sorting machine, or LSM, contained a conveyor belt transport and a series of clerks working the sorting keyboards. Clerks keyed in identifying information that would send letters to specific letter trays that were then deposited into one of 300 chutes. The machine/clerk interface meant that mail could be sorted at an exponentially higher rate, close to 15,000 letters per hour, double the amount that the same number of clerks could do by hand.(1) In 1965, the Department put the first high-speed optical character reader into operation, their first attempt at machines that could read handwriting and process mail accordingly. These early machines worked faster than the human eye, but also had high error rates compared to the clerks. One HPO worker talked about the sorting machines as a hindrance since much of the mail sorted by the machines then had to be fixed by highway or railway mail clerks re-directing that mail to its correct address. But it was just another part of the job.(2) According to Charlie Dahle, “As I began my postal career, the ZIP Code was coming into being. It affected how we learned our states. It, of course, convinced upper management that machines could replace manual distribution.”(3) When Charles was transferred to the St. Paul, Minnesota post office, he saw “that early effort and realized there would need to be much improvement before machines could adequately replace the service that had just been abandoned.”(4)
The White Motor Company, supplier of the majority of HPOs, began a downturn in the 1950s. In 1953, White purchased the Autocar Company but sales dropped during the 1960s. White tried merging with White Consolidated Industries, a company that once made sewing machines, but the federal government blocked this deal, for fear that it was becoming a monopoly. Later, the federal government approved a merger with White Consolidated, which hurt that company more than helped since it was floundering due to White Motor's troubles. During the late 70’s through the early 90’s, White continued to merge and change their focus, and this led to major sales drops. The Post Office saw the decline of White company and this coupled with its changing focus away from the Highway Post Office buses led to the severing of the government’s contract with White and hurting the company’s ability to make a comeback.(5)
In the meantime, on July 2, 1965, postal officials determined that the Washington/Harrisonburg route was no longer saving money. The installation of a postal distribution center near Harrisonburg made the route unnecessary and it was shut down on August 21, 1965. A report stated the reasons for the discontinuation was due to “the effects of the new sectional center distribution established throughout the surrounding regions… and the effectiveness of the re-routing of the Baltimore and Martinsburg to operate between Baltimore and Winchester.”(6) Officials estimated that they could save $60,000 a year by removing the route and that in addition to being covered by the automatic distribution center, they could return to contracting with Star Routes carriers if needed.(7) On July 30, 1965, Virginia Representative John Marsh, Jr. wrote to the Postmaster General on behalf of his constituents regarding the job loss from the removal of the HPO route. Assistant William Hartigan responded on August 2, saying that no postal employees would lose their jobs. The Post Office found places for all the employees affected by the change. In fact, the only employees who didn’t go to work after the removal of the HPO were two clerks who took their retirement after working 37 years.(8) As the bus rolled into the garage on August 21, 1965, the first route of the Highway Post Office was shut down with no fanfare.
The discontinuation of the first route was the beginning of the end. As mail processing machines became more reliable, new distribution centers were created that changed the way mail was distributed to local post offices. On June 30, 1974, the Highway Post Office carried its last piece of mail. Ironically the main reason the HPO service was created was due to the closure of railroad lines but the Railway Mail Service continued to run for at least three more years after the HPOs, ending in 1977.