The transportation sector is a major contributor to greenhouse gas emissions and local air pollution. This dissertation consists of three interrelated chapters that investigate strategies and government policies aimed at fostering sustainable transportation. The first chapter synthesizes recent empirical findings to assess the challenges and prospects of decarbonizing passenger road transportation. It evaluates the advantages and drawbacks of various policy tools designed to encourage modal shifts and enhance vehicle fuel efficiency, and examines the potential roles of electrification and ride-hailing services in transportation decarbonization. The second chapter focuses on fleet electrification. It provides a comprehensive analysis of the global diffusion of passenger electric vehicles, utilizing detailed model-level sales data across the world from 2013 to 2020. The findings reveal that the highly even electric vehicle penetration across countries is partly driven by cross-country variation in consumer incentives and, to a much greater degree, by the availability of charging infrastructure. The analysis suggests that investments in charging infrastructure are considerably more cost-effective than consumer purchase subsidies in promoting electric vehicle adoption. The third chapters aims to understand the provision of public transit in U.S. cities and whether the current fare structure can be redesigned to improve efficiency and equity. It argues that means-tested pricing could more effectively address equity concerns without compromising efficiency gains. Additionally, it compares alternative pricing models, such as cross-modal subsidization and zone-based fares, highlighting their varying impacts on distribution and welfare outcomes.