not only to enter and exit the train protected from the elements, but also to move more easily between cars with the same protection. Dining cars first appeared in the late 1870s and into the 1880s. Until this time, the common practice was to stop for meals at restaurants along the way (which led to the rise of Fred Harvey's chain of Harvey House restaurants in America). At first, the dining car was simply a place to serve meals that were picked up en route, but they soon evolved to include galleys in which the meals were prepared. The introduction of vestibuled cars, which for the first time allowed easy movement from car to car, aided the adoption of dining cars, lounge cars, and other specialized cars. 1900–1950: Transition from wood to steel, new car types In the early 1900s, safety concerns led the railroad industry to transition from wood to steel construction. Steel was heavier but this transition took place simultaneously with a transition to higher-powered locomotives. The Pennsylvania Railroad began building all-steel passenger cars in 1906 due to concerns about fire in the tunnels it was building to access Manhattan's Pennsylvania Station, which opened in 1910. Other railroads followed because steel cars were safer in accidents. During a transition period, some railroads put steel frames underneath wooden cars. By the 1920s, passenger cars on the larger standard gauge railroads were normally between and long. The cars of this time were still quite ornate, many of them being built by experienced coach makers and skilled carpenters. In the United States, the so-called "chair car" with individual seating became commonplace on long-distance routes. With the 1930s came the widespread use of stainless steel for car bodies. The typical passenger car was now much lighter than its carbon-steel cousins of old, though still much heavier than nineteenth-century wooden cars. The new "lightweight" and streamlined cars carried passengers in speed and comfort to an extent that had not been experienced to date. Aluminum and Cor-Ten steel were also used in lightweight car construction, but stainless steel was the preferred material for car bodies. Stainless steel cars could be and often were, left unpainted except for the car's reporting marks that were required by law. By the end of the 1930s, railroads and car builders were debuting car body and interior styles that could only be dreamed of before. In 1937, the Pullman