Crime Mapping

IV. Spatial Crime Research and Planning Interventions

A. Hot Spots

As previously indicated, a large number of studies have demonstrated that criminal events are spatially concentrated. Although the extent of concentration differs between studies, all empirical evidence suggests that a small number of places account for the majority of crime within any given city. Sherman and colleagues (1989) popularized the term hot spot to describe these areas where crime is concentrated. The detection and explanation of these hot spots is a major concern of research in crime mapping. Hot-spot analysis is currently very popular among police agencies because it provides a method to coordinate interventions in emerging problem areas.

A number of studies have demonstrated the benefits of hot-spot analysis to help coordinate police responses to crime. For example, in a randomized experiment in Minneapolis, Sherman and Weisburd (1995) found that concentrated patrol efforts in hot-spot areas produced a significant decline in calls for service. Police responses to crime are not limited to enhanced patrol. In another randomized experiment in Jersey City, New Jersey, Weisburd and Green (1995) found that after identifying drug market hot spots using crime mapping, a coordinated policy of engaging business owners and community members coupled with police crackdowns yielded substantial decreases in disorder calls for service. In fact, a recently conducted meta-analysis on street-level drug enforcement indicated that approaches that focus on community–police partnerships in drug market hot spots were more effective than enforcement-only approaches (Mazerolle, Soole, & Rombouts, 2006). This suggests that the best approach is a coordinated strategy between police officers and community members toward reducing crime in identified hot spots.

B. Community-Level Factors Affecting Crime

When designing strategies to address crime in hot-spot areas, it is important to consider the community context that contributes to emergence and maintenance of hot spots. Neighborhood-level research on spatial crime patterns helps illuminate the factors associated with heightened levels of crime. As previously mentioned, economic depravation, residential mobility, and population heterogeneity all contribute to higher levels of crime in a neighborhood by impeding the development of social ties between residents (Bursik & Grasmick, 1993). Family dissolution and inadequate supervision of adolescents also contribute to increased levels of crime. In fact, the presence of unsupervised adolescents in a community is an important predictor of violent crime in a neighborhood (Veysey & Messner, 1999). Rose and Clear (1998) suggested that prior crime policies that result in mass incarceration may also impair community functioning, because in some communities this represents a substantial loss in the social and human capital on which informal social control depends.

Although many of the structural factors contributing to social disorganization remain outside the control of police agencies, such as concentrated disadvantage and high residential mobility, it remains possible to design interventions to increase social integration and improve collective efficacy. Community policing emphasizes community involvement in responding to crime problems through the creation of police–community partnerships, which should both increase community access to public social control and foster improved trust between community members and police officers. Furthermore, programs designed to increase community integration through increasing resident involvement in local agencies should be helpful in fostering the development of social ties and increasing perceptions of collective efficacy. Finally, if Rose and Clear (1998) are correct, community corrections and offender reintegration efforts should alleviate some of the impact of the mass incarceration policies that have removed offenders from the community. Bursik and Grasmick (1993) provided an extensive discussion on various community-based interventions and provided suggestions for how to improve these programs.

In addition to the previously discussed factors, a fair amount of research has examined the effects of incivilities on crime and the fear of crime within a community. Incivilities, such as poorly tended residences, the accumulation of refuse, graffiti, and public loitering and drunkenness, are signs of disorder. A number of studies have demonstrated that the presence of incivilities in a neighborhood is associated with increased levels of serious crime and with heightened fear of crime among community residents (see Skogan, 1990). Sampson and colleagues (1997), however, suggested that this relationship is spurious and that crime and incivilities result from the same underlying causal process, namely, a lack of collective efficacy. Although the causal role of incivilities in producing crime is in doubt, they may still function as leading indicators of potential crime problems, meaning that mapping incivilities may provide information on communities where hot spots may be emerging.

C. City Features and Crime Locations

In truly comprehensive strategies for addressing crime in hot-spot areas, it is important not only to examine neighborhood-level factors that contribute to the emergence of a crime hot spot but also to consider microlevel place characteristics that promote crime. As Sherman and colleagues (1989) noted, even within high-crime neighborhoods there is substantial variability in the levels of crime. Some places within these neighborhoods experience very low levels of crime, whereas other places are responsible for a substantial amount of the crime.

A number of studies have demonstrated that hot spots of crime tend to emerge around particular features of the urban environment, such as bars and taverns (Roncek & Maier, 1993), fast food restaurants (Brantingham & Brantingham, 1982), schools (Roncek & Faggiani, 1985), public housing (Roncek, Bell, & Francik, 1981), vacant buildings (Spelman, 1993), and public transportation (Block & Davis, 1996). These locations may promote crime by juxtaposing motivated offenders and suitable targets in the absence of capable guardians. Furthermore, the pattern and timing of criminal events in these areas follow the rhythm of legitimate social activity in these areas. For example, crime around bars is more common during evenings and weekends, because more legitimate patrons visit bars during this time. Crime is more common around schools during the school year and after school, because many students interact at this time near school grounds without teacher or parental supervision. Understanding the relationship between the pattern of legitimate social activity and criminal activity around these areas allows researchers and policymakers to design suitable crime prevention strategies.

In addition to identifying the location and timing of criminal events at particular sites, it is important to discern the mechanism through which these areas produce criminal opportunities. Brantingham and Brantingham (1993) discussed the differences between crime generators and crime attractors. Crime generators, such as transit stations, foster criminal activity by bringing both victims and offenders into a location. On the other hand, crime attractors, such as bars and taverns, tend to bring higher proportions of offenders into an area because these locations are tied to patterns of illicit activity. It is important to discern whether a given location functions as a crime generator or a crime attractor, because the appropriateness and effectiveness of intervention strategies may differ by type of location.

There is no shortage of practical policy recommendations for reducing or eliminating criminal opportunities around hot-spot areas. Clarke’s (1997) situational crime prevention model offers a set of 16 different opportunity-reducing strategies. Among those most applicable to location-based interventions are controlling access and entry/exit screening; improving surveillance by officers, civilians, and citizens; deflecting offenders by disrupting routines that promote crime; and facilitating compliance with rules. Use of these strategies to control opportunities for crime may help reduce the risks of victimization in hot-spot areas.

D. Crime Displacement

Unanticipated consequences are always a concern when designing an intervention. For interventions in crime hot spots, crime displacement is of particular importance. After the intervention is implemented and crime opportunities are reduced, it is possible that offenders simply relocate their activities to areas outside the intervention site. For example, if a police crackdown on drug trafficking is initiated at a particular intersection that is a hot spot for drug dealing, it is possible that offenders will simply move to a nearby intersection, and drug sales will continue. Other types of crime displacement, such as offenders committing crime during different times, offenders selecting different targets, or even offenders committing different types of crimes, also are possible. Given the wide ranges of different responses that might constitute crime displacement, it is difficult to conclusively demonstrate that crime displacement did not occur during a particular study. For this reason, any researchers or policymakers implementing place-based intervention strategies should be keen to the possibility of crime displacement. Fortunately, the empirical literature on crime displacement is decidedly mixed, and it appears that many interventions do not lead to appreciable crime displacement effects (Clarke, 1997).