Over the past 40 to 50 years, most American cities have experienced significant increases in automobile use. Now, to offset increasing energy use and greenhouse gas emissions, many are contemplating measures to reduce automobile use. This study examined Hartford, Connecticut, and Cambridge, Massachusetts, which exhibited an increase and a decrease in automobile use, respectively, between 1960 and 2007. It is hoped that these cities provide lessons in how to successfully reduce automobile travel. The study focused on the cumulative effects of historical policy decisions over decades on parking provisions and changes in travel behavior. The results of this analysis suggest that parking policy affects incremental changes in parking provision that may greatly influence gradual changes in automobile use over time.