An economic analysis of United States public transit carbon emissions dynamics

During a time of rising concern about climate change, the urban public transit sector has not significantly reduced its carbon footprint. Using data from the nation's transit agencies over the years 2002–2019, we document that the energy efficiency gains of US public transit lagged the gains of European public transit and the US private transportation. The carbon footprint of a transportation provider depends on scale, composition, and technique effects. We use this accounting framework to explore several possible explanations for our findings. We contrast the incentive effects that a private entity versus a public transit agency faces in decarbonizing.