Today we're going to discuss the history of the postal service. In the 19th century, mail was delivered by train, which was fast but limited to major routes. Then, in the early 20th century, the introduction of motor vehicles allowed for more flexible door-to-door delivery. However, it wasn't until the 1920s that airmail became practical, significantly reducing delivery time for long distances. Interestingly, the first regular airmail service in the United States began in 1918, but it was initially used only for government documents. By the 1930s, commercial airlines took over airmail, making it more efficient and cheaper for the public.