Spatiotemporal Context for Daylight Saving Time-(DST-)Safety Interactions in the Contiguous United States

Motor-vehicle crashes are a leading and persistent cause of unintentional deaths in the United States. Scholarship to understand how manmade interventions and natural phenomena interact to effectuate such calamitous outcomes is longstanding and ongoing. One manmade intervention with long interest in the literature is daylight saving time (DST). Unfortunately, such interest engenders little unanimity on how the natural phenomena attributable to DST interact with travel behavior to affect the frequency and severity of motor-vehicle crashes. In order to advance knowledge on DST-safety interactions the study adopts a multilevel model approach to explore spatial and temporal heterogeneity in fatal crashes the explication of which is not yet evident in the literature. Results suggest analyses of the forty-eight states plus the one state equivalent (District of Columbia) in the contiguous United States mask differences from time zone to time zone on the effects of independent variables known to affect the frequency and severity of fatal crashes. Results also suggest time-of-day and time-zone safety effects are indeed evident. Research which adopts a multilevel model approach to analyze DST-transition safety effects is ongoing. Policy implications highlight the importance of governmental efforts to limit licensure and monitor behavior in order to most effectually decrease the number of fatalities in such motor-vehicle crashes.