Wheels on the Bus: Impact of Vaccine Rollouts on Demand for Public Transportation

The coronavirus disease 2019 (COVID-19) pandemic led to sharp declines in public transit ridership, resulting in budget shortfalls and service cuts that disproportionately affect vulnerable riders who lack alternative transportation options. Understanding the effect of vaccination on public transportation demand is important for planning for demand recovery as vaccination efforts progress. This study examines this effect, with a particular focus on heterogeneous effects across population groups. Estimating the impact of vaccination is challenging due to a lack of fine-grained data and potential endogeneity issues. To overcome these hurdles, we exploit the distinctive features of the COVID-19 vaccination progress to identify an instrumental variable. By merging the U.S. COVID-19 vaccination data with county-level mobility data, we construct a sample that links vaccination rates to the demand for public transportation and follow the instrumental variable approach to estimate the impact. We show that higher vaccination rates led to increases in public transportation demand, as reflected in mobility data from transit stations. Furthermore, we find the effect of vaccination on public transit demand is 50% greater in counties with a larger uninsured population and 80% greater in counties with a higher share of residents without a college degree. Our findings demonstrate that as vaccination efforts progress, public transit agencies should proactively strengthen their infrastructure to accommodate the anticipated rise in ridership. A strategic, forward-looking approach will be critical to ensuring a sustainable and effective recovery of public transportation systems.