Homicide in Chicago from 1890 to 1930: prohibition and its impact on alcohol- and non-alcohol-related homicides.

The aim of the current paper is to examine the impact of the enactment of constitutional prohibition in the United States in 1920 on total homicides, alcohol-related homicides and non-alcohol-related homicides in Chicago. Data are drawn from the Chicago Historical Homicide Project, a data set chronicling 11 018 homicides in Chicago between 1870 and 1930. Interrupted time-series and autoregression integrated moving average (ARIMA) models are employed to examine the impact of prohibition on three separate population-adjusted homicide series. All models control for potential confounding from World War I demobilization and from trend data drawn from Wesley Skogan's Time-Series Data from Chicago. Total and non-alcohol-related homicide rates increased during prohibition by 21% and 11%, respectively, while alcohol-related homicides remained unchanged. For other covariates, alcohol-related homicides were related negatively to the size of the Chicago police force and positively to police expenditures and to the proportion of the Chicago population aged 21 years and younger. Non-alcohol-related homicides were related positively to police expenditures and negatively to the size of the Chicago police force. While total and non-alcohol-related homicides in the United States continued to rise during prohibition, a finding consistent with other studies, the rate of alcohol-related homicides remained unchanged. The divergent impact of prohibition on alcohol- and non-alcohol-related homicides is discussed in relation to previous studies of homicide in this era.