the late 19th century, railroads often had built redundant routes to a competitor's road or built through sparsely populated regions that generated little traffic. These marginal rail routes survived the pricing pressures of competition, or the lack of revenue generated by low traffic, as long as railroads provided the only efficient economical way to move goods and people across the United States. In addition to the intercity passenger network running on Class I and II railroads, a large network of interurban (trolley or "street running") rail lines extended out from the cities and interchanged passenger and freight traffic with the railroads and also provided competition. 20th century The advent of the automobile signaled the end of railroads as the predominant transportation for people and began a new era of mobility in the United States. The early 20th century Lincoln Highway and other auto trails gave way in the 1920s to an early national highway system making the automobile the primary mode of travel for most Americans. Interurban rail service declined, followed by trolley cars due in part to the advent of motorized buses and the lack of dedicated rights-of-way but also by deliberate efforts to dismantle urban rail infrastructure (see Great American streetcar scandal). The scarcity of industrial materials during World War II slowed the growth of the automobile, briefly reemphasizing much of the nation's declining rail network. In the 1950s, the United States renewed building a network of high-capacity, high-speed highways to link its vast territory. The most important element is the Interstate Highway system, first commissioned in the 1950s by President Dwight D. Eisenhower and modeled after the Italian autostrada and the German Autobahn system. Postwar By 1945, nearly every city in America had at least one electric tram company providing intra-city transportation. There were an estimated 36,377 light rail vehicles in operation. Increased automobile ownership cut this number by 1/3 by 1965. The airline industry began to successfully compete with intercity rail as a result of government investment, which suffered a loss of ridership. As the civil air transportation network of airports and other infrastructure expanded, air travel became more accessible to the general population. Technological advances ushered in the jet age, which increased airline capacity, while decreasing travel times and the cost of flights. The costs of flying rapidly decreased intercity rail ridership by the late 1960s to a point where railroads could no longer profitably