The earliest train cars, dating back to the late 1820s and 1830s, were simply coaches and built to resemble stagecoaches of the day. Having no center isle or protection from the outside elements, aside from a roof, they were rudimentary at best and dangerous because they offered no protection from the early locomotives of the day which were severely prone to boiler explosions. By the mid/late-19th century railroads began diversifying into different passenger car types such as diners, RPOs, baggage/combines, and early sleepers. This period also saw the development of the standard coach car, whereby it featured a center aisle for passengers to more easily exit and enter the car, the same type of setup you still see today particularly on buses.
Even by the end of the 19th-century most cars were still built almost primarily with wood, save for the support structures (such as the center support beam, trucks, and other necessary railroading components) which were made of early steel, which by the mid-1850s had become inexpensive enough to be used in widespread applications within the railroad industry. However, also around this time also what were known as "heavyweight" passenger cars were introduced, built almost entirely from steel, hence their name. Steel not only allowed the car to be stronger but also reduced the chance that it would so easily catch fire. However, steel was quite heavy and with the advent of lightweight materials in the 1930s, when the streamliner was born, passenger trains became much lighter and cost less to operate just through sheer weight.
The streamliner era of the 1930s saw the most advances in passenger train car construction as company's spared no expense wooing passengers to their trains. Comfort, relaxation, and stunning interior and exterior designs became the norm for a railroad's most prominent passenger train(s). These amazing trains during the 1930 to 1950 era are commonly remembered as the "Golden Age" of passenger railroad travel with sleek streamlined equipment and a round-ended observation car on the rear to complete the look. Many of these were built by the most famous names in manufacturing such as Pullman-Standard and the Budd Company.
Just as a point of reference, all of the passenger car equipment built for railroads through roughly the 1950s is commonly referred by railfans and historians as varnish, an endearing term that gained prominence because of the grand designs, architecture and construction built into the cars. This was especially true prior to the streamliner era when car construction still carried a Victorian style and featured much interior plush and wood designs, often employing the use of master carpenters and woodworkers to complete the work.
With the advent of Amtrak in 1971 not only did romance of passenger
railroad travel slowly lose its appeal (mostly because a decline in the
service provided, which had actually been taking place since the 1960s
when many railroads began to give up on their passenger train
operations) but car construction technology also declined. By the 1970s
many of the most famous manufacturers had left the business or were in
severe decline, such as Pullman and Budd. Today, Amtrak service has
continued to improve but the days of relaxing in a rear observation car
or enjoying a five star meal prepared by an on board chef are no more.
Hopefully, though, one day these services will return to the public.
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Passenger Train Cars