A long-advertised benefit of ridesharing is that it reduces the necessity and temptation for drunk driving, yet not many studies have quantified the true link between the two. In order to remediate this, a study led by past PISC trainee Cristopher Morrison, PhD, and contributed to by External Advisory Board member David Humphreys, PhD, analyzed 2018-2019 trip-level rideshare and motor vehicle crash data from the Chicago Data Portal. It found that the average rideshare trip density was 69 per square mile in the vicinity of alcohol-involved crashes and 105.7 per square mile in the vicinity of non alcohol-involved crashes. The study also states that a standard deviation increase in rideshare trips per square mile at a crash location was associated with a 23% decreased chance that the crash had alcohol involved. Such results imply that ridesharing does indeed replace motor vehicle trips made by alcohol-impaired drivers, although further investigation is necessary.