Numerous studies have shown that later school start times (SST) are associated with positive student outcomes, including improvements in academic performance, mental and physical health, and public safety. While the benefits of later SST are very well documented in the literature, in practice there is opposition against delaying SST. A major argument against later SST is the claim that delaying SST will result in significant additional costs for schools due to changes in school bus transportation strategies. However, to date, there has only been one published study that has quantified some of the potential economic benefits of later SST in relation to potential costs. The present study investigates the economic implications of later SST by examining a policy experiment of a statewide shift in school start times to 8:30 a.m. and its subsequent economic effects. Using a novel macroeconomic modeling approach, the study estimates changes in the economic performance of 47 U.S. states following a delayed SST, which includes the economic benefits of higher academic performance of students and reduced car crash rates. The benefit-cost projections of this study suggest that delaying school start times is a cost-effective, population-level strategy that could have a significant impact on public health and the U.S. economy. From a policy perspective, these findings are crucial as they demonstrate that significant economic gains resulting from the delay in SST accrue over a relatively short period of time following the adoption of the policy shift.