© 2023 World Conference on Transport Research SocietyThis study aims to understand the reasons behind people's modal preferences in commuting trips, which contribute to transportation-related problems and to develop and prioritize policies that increase the use of sustainable modes. For this reason, in this study, a comparative case study was conducted to evaluate the factors that lead to choosing or not choosing sustainable modes. Commuting trips in San Francisco, San Diego, Los Angeles, San Jose and Sacramento, which are large cities with high automobile dependency and many potential alternatives to driving, were examined using the National Household Transportation Survey (NHTS) and spatial data. The factor classifications suggested in the literature were shaped according to the scope of the study and examined on four main headings. Proximity analyses were completed in the GIS environment to evaluate the environmental effects. The effects of all factor parameters on modal preferences were calculated for each mode of transport in the study with Binary Logistic Regression analyses. As a result of the comparative analysis, the barriers to using sustainable transportation modes in cities and the reasons for driving are determined. As a result, long-term policies were determined and prioritized with literature to manage these causes and barriers. The results show that modal choices are affected by many different parameters, the reasons differ locationally, and accordingly, the policy measures in each region should be different.