Short, silent film demonstrating how "mail-on-the-fly" worked.
The original film is in the collection of the Library of Congress.
“The night was coal black, and it was awkward holding onto the mail sack with one hand, the other on the crossbar . . . watching for the faint glow of the light on the crane. . . . The wind tried to steal your breath away. . . . There was both relief and satisfaction when I heard the 'whing' of the pouch as it was snatched.”
—L. E. Davis, RPO Clerk
Clerks always knew where they were so they never missed an exchange. Courtesy of the National Postal Museum Library, Smithsonian Institution Libraries
As early as 1865, before the arrival of mail cranes, mail was exchanged on nonstop trains, but to do so, engineers had to slow trains down to a crawl so clerks could exchange the mail by hand. This system, both inefficient and dangerous, was soon scrapped. The first track side Railway Mail Service cranes were wooden, F-shaped, mechanisms. They were soon replaced by a simple steel hook and crane.