A large theoretical literature in sociology connects increasing rates of incarceration to contractions in the labor market. But evidence for the economic causes of incarceration is mixed. We use a shock to the southern agricultural labor market to study the political economy of incarceration in the U.S. South in the early twentieth century. From 1915 to 1920, a beetle called the boll weevil spread across the state of Georgia, causing cotton yields and the prevalence of tenant farming to fall. Using archival records of incarceration in Georgia, we find that the boll weevil infestation increased the rate at which African Americans were admitted to prison for property crimes. The effects for whites and for prison admissions for homicide were much smaller and not statistically significant.