While the vast streetcar system in Los Angeles was wildly successful since early in the 20th century, it was doomed to extinction in the era of automobiles and bus routes. The streetcar system was sold to National City Lines in 1945, a company whose investors included car-centric companies such as Firestone Tires, Standard Oil of California, and General Motors. Instead of enhancing the city's transportation network, the company, which then changed its name to Los Angeles Transit Lines, began to introduce buses to the city's streets. By the early 1950s, many trolleys (including the "Yellow Cars") were converted to buses, despite the public's opposition.
This change is now referred to as the Great American Streetcar Scandal. General Motors was blamed for acquiring and demolishing trolleys not only in Los Angeles, but around the country. In 1949, they were indicted for scheming to control the streetcar system, but was acquitted of the charges, fined only $5,000. The scandal remains a part of urban lore, inspiring the central plot of the 1988 movie Who Framed Roger Rabbit?
National City Lines' involvement with the trolleys was undoubtedly a contributing factor in the system's downfall, but there are other factors as well. The Great Depression made it difficult for the railway to keep up with maintenance and labor costs, and the construction of new highways funded by federal dollars created jobs and expanded the transportation system beyond the trolley's reach.
White flight from Highland Park was another reason. The growing suburbs were not accessible by streetcar, and as Los Angeles' newest suburbanites purchased their first automobiles, traffic made the trolleys more difficult to run in the core city.
In 1963, the Los Angeles Metropolitan Transit Authority purchased the remaining streetcar lines and replaced them all with diesel buses. The end of the 20th century, however, saw the reemergence of the Los Angeles Metro system, with the introduction of the Blue Line light rail system in 1990. The Gold Line began service in Highland Park and its surrounding neighborhoods in 2003.
Propaganda Arthur Snyder describes the decline of the trolley system in Los Angeles, accelerated by the constant news coverage of trolley accidents and a possible conspiracy amongst the automobile, petroleum and tire companies.