The geographic concentration and diffusion of crime and deviancy are longstanding criminological inquiries, yet few studies have examined how certain illicit behaviors transcend neighborhood borders and connect neighborhoods in patterns of crime and deviancy. A structural neighborhood interdependence may account for the enduring nature and spread of crime, making it critical to understand how neighborhoods are connected in crime patterns to guide crime prevention and disruption efforts. This study examines neighborhood interdependence through the case of repeat buyers of commercial sex in illicit massage businesses in a metropolitan city in the United States. By frequenting venues for illicit commercial sex in multiple neighborhoods, buyers create inter-neighborhood connections through which the demand for an illicit market can spread across neighborhoods. Using online review data about buyers of commercial sex, this study analyzes this neighborhood interdependence as a network comprised of nodes (“neighborhoods”) and edges (“connections between neighborhoods”). Exponential random graph models were used to analyze how characteristics of neighborhoods, the space between neighborhoods, and the overall network of neighborhoods explain inter-neighborhood connectivity in an illicit market for commercial sex. The implications for research, policy, and practice will be discussed.