As an urban-related issue, crime has been extensively discussed in many research areas including ecology, sociology, geography, economics, and political science. For example, income inequality, wage structure, and labor market are considered as important contributors to the crime rate from the perspective of economics (Freeman 1999). Researches have also shown that there exists a strong relationship between crime, the criminal, and the urban environment, which provides an environmental perspective that can explore and analyze crime at different geographic levels (Wortley and Mazerolle 2008).
Nowadays, the environmental perspective in criminology has been popular among many urban and criminological research areas and has gradually shaped a multi-disciplinary approach: environmental criminology. In this section, we will first depict the historical roots of understanding urban crime from an environmental perspective. We then outline the key concepts and theories in environmental criminology.
2.1 Historical Roots in Understanding Urban Crime: An Environmental Perspective
Traditional criminological research focuses on the criminality of offenders and explores how biological factors, life-course experiences, and social forces influence and create criminals. Therefore, the crime is seen as the expression of the offender’s deviance, influenced by events that occurred in his or her childhood. However, the concerns of the environmental perspective differ greatly from other criminological approaches. They argue that the criminal is just one portion of the crime event, and the concern is the dynamic of crime pattern, such the time, space, victim, and type.
In addition, there has been an enduring interest in place (environmental perspective) in criminology (Weisburd et al. 2012). Different crime theories explain crime at different spatial levels, ranging from the country level, province level, city level, and community level to the street segments level. Brantingham and Brantingham (2017) suggested three geographic levels of analysis—the macro-level, the meso-level, and the micro-level—within the domain of environmental criminology.
This classification matches the development of the unit of analysis in geographic analysis, which also reflects the historical roots of understanding urban crime from an environmental perspective. Briefly, studies started in the nineteenth century were mainly referred to as macro-level (e.g., countries, provinces) analysis (Guerry 1833).
Then, the early twentieth century witnessed the urban crime studies led by the Chicago School, which mainly focused on the meso-level of analysis, such as cities and big urban areas (e.g., Burgess 1928). Lately, micro-level (e.g., community and street segments) studies, starting from the late twentieth century, have attempted to achieve a fine-resolution analysis of urban crime (e.g., Sherman and Weisburd 1995), which makes crime more predictable than before.
2.1.1 Macro-Level Studies
Macro-level studies focus on analyzing crime distribution between countries, states, or provinces. The world’s first crime map was made by Guerry and Balbi (1829). Leveraging the geographic map, they demonstrated that crime in urban areas was more than that in the rural areas in some provinces in France.
Many interesting findings were obtained based on macro-level studies. For example, Quetelet (1831) explored the correlations between crime and many factors (e.g., levels of poverty, ethnicity, the attraction of city) in different cities of different countries. Especially, in terms of common sense, poverty may cause crime, even if violent crimes were more prevalent in poorer rural districts, and property-related crimes showed a higher level in wealthy districts than in rural areas. Such findings indicated that poverty was not highly associated with property crime, but the opportunities existed because wealthy provinces contained more valuable targets (Guerry 1833).
After that, similar studies have compared crime between different areas, such as countries. In the mid- and late nineteenth century, empirical studies in England showed distinctive differences in crime levels and rates across various counties. This study also reported higher crime rates in urban and industrialized areas than in rural areas (Mayhew 1851).
2.1.2 Meso-Level Studies
Meso-level studies involve the analysis of crime patterns within cities or metropolises. Studies at this level investigate crime concentrations based on a medium scale of geographic areas. For example, concentration tends to exhibit a difference between central urban areas and suburbs.
In the 1900s, a group of American sociologists known as the Chicago School took a leadership role in the development of environmental criminology at the meso-level. They treated crime as a social problem that is spatially distributed in urban areas. Park (1915) argued that urban life must be studied for crime analysis, such as “its physical organization, its occupations, and its culture” and especially the changes therein. Neighborhoods in his view were the elementary form of social cohesion in urban life. In addition Thomas and Znaniecki (1927), introduced an important concept of social disorganization, which means a decrease of the influence of existing social rules of behavior upon individual members of a group. This concept has drawn attention to communities and neighborhoods. Then, Burgess (1928) split the city into five concentric rings, and he also suggested that the urban functional zone strongly shaped the crime pattern. Inspired by the zone model developed by Burgess (1928), Shaw and Mckay firstly detected the spatial distribution of urban crime by an original method of crime mapping (Shaw and Mckay 1942). Shaw and Mckay (1942) also explored the spatial patterns of juvenile delinquency in Chicago City by comparing the spot maps of delinquency rate with the urban racial zone map and showed that crime rates varied over the urban area.
2.1.3 Micro-Level Studies
Micro-level studies examine crime patterns based on spatial areas at a fine resolution, such as the community level, the street level, and prime locations. In the 1980s, urban crime researchers still focused on using social disorganization theory to explain the dynamics of crime patterns at the community level. For example, Bursik Jr (1986) found that long-term crime stability was affected by community stability. More typically, Sampson et al. (1997) proposed a concept of collective efficacy which significantly influences crime in different communities. Since then, research attention has been shifted from macro- or meso-level analysis to micro-level crime study (Weisburd et al. 2009).
After the emergence of various sophisticated spatial analysis tools (e.g., GIS) in the late twentieth century, researchers could explore how various environmental factors influence specific crime locations in practice. These micro-level areas include buildings, addresses (Sherman et al. 1989), street segments (Johnson and Bowers 2010), or locations (Sherman and Weisburd 1995). Current studies confirm that street- or location-level analyses about crime sustainably enrich environmental criminology and make crime more readily forecasted (Cozens 2011).
2.2 Theoretical Concepts in Environmental Criminology
Environmental criminology (i.e., the environmental perspective in criminology) emphasizes the influence of the environment on crime patterns, considering that crime is the convergence of offenders, victims, and law enforcement at particular times and places (Wortley and Mazerolle 2008). Research in this area explores the spatiotemporal patterns of crime events and explains the patterns by referring to the features from the urban fundamentals—street networks, road segments, buildings, and so on. Consequently, the strategies of crime prevention derived from the explanations are becoming popular among both urban managers and inhabitants who want to manage and live in an environmentally friendly city.
Environmental criminology is mainly based on three hypotheses, which have their own implications for crime prevention (Scott et al. 2008). First, apart from the offender’s ability or the accessibility of victim information, the instant environment where crime occurs could significantly affect the offender’s behavior by affecting the criminal’s person–situation interaction. In this principle, environmental criminology not only argues that crime is derived from criminogenic individuals but also aims to explore and explain how the environment affects the offender and why some places are criminogenic. Second, the spatiotemporal distribution of crime is not random. Crimes are spatially concentrated at places where the environmental features would promote crime opportunities. They are also concentrated around the intersection of routine activities between offenders and victims. Such crime patterns explain why crime hotspots are stable during extended periods in particular areas, a phenomenon known as the law of crime concentration (Weisburd 2015). Third, knowledge of the criminogenic environment and crime patterns could help law enforcement to allocate resources to mitigate crime in a particular location. Practically, environmental criminology could provide new insights into solutions for proactive crime prevention, such as crime prevention through environmental design, or situational crime prevention, which will be further discussed in the next section in the context of urban security implementation issues.