School of Public and International Affairs

Based on the 2001 and 2009 National Household Travel Surveys, this paper analyzes trends and determinants of multimodal car use in the U.S. during a typical week by distinguishing between (1) monomodal car users who drive or ride in a car for all trips, (2) multimodal car users who drive or ride in a car and also use non-automobile modes, and (3) individuals who exclusively walk, cycle, and/or ride public transportation. We find that during a typical week a majority—almost two thirds—of Americans use a car and make at least one trip by foot, bicycle, or public transportation. One in four Americans uses a car and makes at least seven weekly trips by other modes of transportation. Results from multinomial and logistic regression analyses suggest there may be a continuum of mobility types ranging from monomodal car users to walk, bicycle, and/or public transportation only users—with multimodal car users positioned in-between the two extremes. Policy changes aimed at curtailing car use may result in movements along this spectrum with increasing multimodality for car users.