Jarman MP, et al. - As there is a lack of information on prehospital time or distance from the site of an injury event to the treating hospital, validation of zip code–based estimates of ambulance driving distance was sought. This validation may support future use of administrative data sets in the study of emergency medical services, trauma systems, and injury outcomes. Researchers identified the criticality of proximity to hospital facilities and the duration of the prehospital interval when studying injury outcomes.