The analysis determined that agglomeration economies indeed had an important impact on the spatial clustering of illegal drug dealers in Philadelphia, implying that focused police attention to remove these economically favorable places would result in the diffusion of benefits as prior research discovered. Agglomeration economies illustrate that taking the largest and most profitable site from illegal drug dealers will make dealing in the surrounding neighborhoods less rather than more profitable and lead to a smaller marketplace overall. Illegal drug markets remain a serious problem for American society. There is a debate over whether police attention focused on an illegal drug market causes dealers to spatially displace their activities, resulting in no positive impact on the aggregate level of illegal drug sales in the city. The alternative perspective is that focused police attention lowers the rate of illegal drug sales in the city. Recent urban research demonstrates that focused police attention does not simply move illegal drug dealing around the corner. This analysis explains the commonality of this finding in other cities, specifically Philadelphia, PA. Tables, figures, and references