Comprised of three papers, this dissertation examines how changes within the urban environment affect crime and the criminal justice system. Collectively, these three papers address policy-relevant issues for urban communities that include police-community relations, the caretaking role of the police, firearm-related violence, blighted and vacant land, the opioid epidemic, and access to treatment for opioid use disorder. The first paper assesses the place-based effects of outpatient methadone maintenance treatment facilities on crime in Philadelphia. The analysis in this paper uses spatial and temporal variation in OMMT facility presence during an eleven-year period (2007-2017) to determine these effects. Within a 200-meter radius, the presence of an OMMT facility caused a significant decrease in property and total crime but a significant increase in drug and violent crime. There were no significant effects on crime outside of the 200-meter radius. The second paper evaluates the effect of randomized vacant lot remediation on the frequency of shootings that result in serious injury or death. The analysis in this paper uses data from a 2013 randomized controlled trial was conducted in Philadelphia involving 541 vacant lots. Some vacant lots were remediated, other vacant lots received a lesser level of remediation, and the remainder received no remediation. Over a 60-month period, remediating lots significantly reduced shooting incidents; there was no evidence that the interventions displaced shootings into adjacent areas. The third paper tests whether a high-profile death-in-police-custody incident in Baltimore affected community reliance on the police, as measured through citizen calls requesting police assistance for non-criminal caretaking matters. This paper presents a Negative Community-Police Relationship Index Score that operationalizes the risk of a negative community-police relationship for a given location within Baltimore based on factors such as the percentage of residents living in poverty and the percentage of vacant residential housing units. Even in high-risk sections, the death-in-police-custody incident did not significantly affect community reliance on the police for non-criminal caretaking matters.