The Protective Role of Collective Efficacy Against Illicit Drug Availability at the Street Level: A Longitudinal Analysis.

Illicit drug use remains a persistent public health concern in the USA. A growing body of research demonstrates that access to illicit drugs plays a central role in shaping patterns of drug use. Although prior studies have identified the importance of opportunity structures and broader neighborhood structural conditions in explaining variation in drug activity across places, less attention has been paid to the role of informal social control in reducing illicit drug availability, particularly at the microgeographic level. Drawing on the concept of collective efficacy, defined as shared trust among residents and their willingness to intervene for the common good, this study examines whether collective efficacy functions as a protective factor against drug availability at the street level. We used two waves of longitudinal survey data collected from crime and drug hot spots and non-hot spots in Baltimore City, Maryland, along with physical observation measures, police calls for service data, and open-source indicators to account for key confounding factors. Multilevel binomial logistic regression was used to estimate the probability that residents observed illicit drug sales on their street, accounting for differences in the number of respondents across streets and the clustering of street segments within communities. We found that collective efficacy served as a key protective factor, significantly reducing illicit drug availability at the street level over time (OR = 0.69, 95% CI = 0.51-0.94). These findings underscore the importance of community-based mechanisms of informal social control at the microgeographic level in addressing urban drug problems.