Auto ownership and mileage per car are shown to vary in a systematic and predictable fashion in response to neighborhood urban design and socio-economic characteristics in the Chicago, Los Angeles, and San Francisco regions. In all three cases, average auto ownership is primarily a function of the neighborhood's residential density, average per capita income, average family size and the availability of public transit. Similarly, the average annual distance driven per car is a strong function of density, income, household size and public transit, and a weaker function of the pedestrian and bicycle friendliness of the community. The similarity of these relationships among the three metro areas, despite their differences in geography and age, suggests that similar relationships may be consistent throughout the United States or worldwide. The application of the results to other metro areas is discussed. The dependence of driving on the policy-related variables of residential density, transit access, and pedestrian and bicycle-friendliness may provide policy makers with additional tools for reducing the costs and environmental impacts of transportation.

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Email:  john.holtzclaw@sierraclub.org