How has vehicle fuel consumption in comparison to miles traveled changed since 1960? What is the likely cause for this change?

After World War II, economic growth, population growth, rapid suburbanization, and the closing of some public transit systems led to more reliance on personal vehicles for transportation. The number of cars and trucks in the United States increased dramatically, as did the number of highways. One result of the rapid increase of motor vehicles was air pollution, especially in cities, that had serious impacts on public health and the environment.

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