Crime and the Built Environment

In her seminal 1961 book, The Death and Life of Great American Cities, Jane Jacobs argued that the vitality of urban life depends critically on the design of communal spaces. With respect to public safety, she argued that the police, while necessary, cannot make a community safe on their own, and that sustainable safety is ultimately created by “an intricate, almost unconscious network of voluntary controls and standards ... enforced by the people themselves.” In short, when public space is used and monitored by members of the public, these spaces are made safe for the public to enjoy. On the other hand, public spaces that are hidden from prying eyes — such as public housing stairwells or blocks where law-abiding people dare not venture — can become hot spots for crime and disorder.  

This idea — that communal spaces can be designed to empower ordinary citizens to protect themselves — inspired the next generation of urban planners and public safety advocates to coin the term “crime prevention through environmental design,” usually referred to using the acronym CPTED. Architects might appeal to CPTED principles to design a building that is characterized by more defensible spaces. City planners might appeal to CPTED principles in considering changes to a city’s landscape such as shifts in zoning laws or the placement of roadways or the design of a neighborhood park. Similarly, public safety advocates sometimes appeal to CPTED principles in advocating for the remediation of disorderly conditions such as abandoned buildings, vacant lots and poor nighttime lighting.

Can making changes to the built environment deter crime and increase public safety? People of all political stripes should be rooting for an affirmative answer to this question. After all, deterring crimes before they happen is cheap. Punishing offenders after a crime has occurred is far more expensive, for both victims and for society. In short, deterrence is like a Black Friday deal — a way to make every public safety dollar go further (and something that both progressives and conservatives might agree upon).  

But can crime actually be deterred by improved street lighting or community gardens? To many, that might seem like an overly optimistic — or even simplistic — idea. Does a potential robber see a community garden and develop a soft spot for his potential victim? Does a gang member decline to assassinate a rival gang member because he notices that a few houses have been fixed up on his rival’s street? Was Jane Jacobs overly idealistic in arguing that well-designed public spaces can empower community members, with the help of the police, to take back control of their communities?

As it turns out, a growing academic literature on CPTED-inspired interventions suggests that Jane Jacobs was very much ahead of her time. The available research now includes high-quality evidence — including “gold-standard” evidence from randomized controlled trials — in favor of a host of CPTED-inspired interventions such as increasing the availability of trees and green space, restoring vacant lots, enhancing the effectiveness of street lighting and improving networks of visual surveillance.

Abandoned Spaces

As nearly any police officer or community member will tell you, crime tends to cluster around abandoned properties. Vacant houses can become a magnet for the drug trade, and vacant lots offer the conditions for drug dealers and gang members to stash guns and other contraband. But is the relationship actually causal or is it simply an interesting correlation? And can public safety in disadvantaged communities actually be improved through government action? 

In order to answer these questions, researchers from the University of Pennsylvania have worked with city planners to evaluate a host of community programs in Philadelphia that were designed to improve the quality of public spaces in some of the city’s most challenged neighborhoods. The researchers have found that when vacant lots were improved by removing trash and debris, planting new grass and a small number of trees and installing low wooden fencing — and maintained for a period of time — disorderly conditions and crime, even serious violent crimes like shootings, declined.  

Crime reduction has likewise followed the remediation of abandoned properties, a requirement imposed on landowners by a city ordinance which required all properties to have functioning windows and doors. Importantly, in all cases, the researchers found little evidence that crime was merely pushed around the corner to a nearby area which did not receive any remediation. This finding mirrors many others from criminological research that find that offenders are strongly tied to place and do not shift easily to new areas.  

Street Lighting

Enhanced street lighting is a form of crime control that has been around, in one form or another, for millennia. Oil lamps were used to improve nighttime public safety in the Greco-Roman world at least as far back as 500 B.C. By some accounts, street lighting was introduced in the United States by Benjamin Franklin, who designed his own candle-based street light, first used in Philadelphia, as early as 1757.

Does crime, in fact, respond to ambient lighting? Some critical proof-of-concept can be found in recent research that considers the public safety impact of daylight savings time. When we turn our clocks backwards or forwards by an hour, lighting conditions change suddenly and drastically for a given hour of the day. What happens to street crimes at 7 p.m. when, all of a sudden, it is dark outside instead of light? Research from the United States and Chile suggests that crime increases.  

With respect to lighting interventions that are available to policymakers, recent research considers whether the addition of large and exceedingly bright mobile lighting towers to New York City’s public housing developments led to a reduction in crime. That research, a randomized controlled trial, found that the additional lighting reduced nighttime crime — including serious crimes like assault and robbery — appreciably, with effects that were sustained for at least three years. More broadly, a 2022 review of the literature finds that while the effects of street lighting vary widely depending on the quality and the setting of the intervention, on average, improved lighting reduces outdoor crimes by approximately 14 percent. While lighting is no panacea, the available evidence suggests that it can make an important difference.

Surveillance Cameras

When Jane Jacobs wrote The Death and Life of Great American Cities in 1961, a network of surveillance cameras blanketing a city was nearer to science fiction than to reality. But today, homeowners and business managers alike can purchase a doorbell camera for as little as $50, and cities have made increasing investments in adding closed circuit television (CCTV) cameras, sometimes monitored and sometimes not, to highly traversed public spaces. Leveraging video surveillance has expanded the number as well as the quality of witnesses, potentially changing the calculus of committing a crime in a public space.

Does crime, in fact, respond to the proliferation of video surveillance cameras? Forty years of research suggests that the answer is often yes, especially when cameras are actively monitored by law enforcement. Adding video surveillance appears to be especially effective in reducing theft from parking lots, a type of crime that is less impulsive and more likely to be planned. Research also supports the idea that crime in residential communities is responsive to enhanced surveillance. In one recent study, a randomized experiment in Newark, New Jersey, adding more intensive monitoring to CCTV networks led to a decrease in crime, including violent crimes. 

Myopic Offenders

Why are CPTED-inspired interventions effective? Human nature offers some important clues. Though criminal offenders are sometimes thought to be maniacally skillful and highly motivated, in practice, like the rest of us, they are often lazy and not especially planful. This is, in part, why most offenders commit crimes within a few blocks of where they typically spend time rather than traversing the city in search of more lucrative and poorly defended targets. It is also why many crimes are simply crimes of opportunity, sensitive to factors like weather and the availability of potential victims.

Criminal offenders, like many human beings, also tend to be myopic, weighing the immediate costs and benefits of their actions more highly than more temporally distant consequences which may or may not come to fruition. For someone who is present-oriented, the unlikely prospect of a longer prison sentence may be less likely to deter crime than more immediate concerns like the presence of witnesses or the potentially lethal combination of bright lighting and CCTV. By leveraging the present orientation of many offenders, CPTED-inspired interventions have the potential to double down on deterrence.

Broken Windows

Interestingly, some of the strongest evangelism for the importance of the built environment comes from the seminal 1982 article “Broken Windows,” by the criminologist George Kelling and the political scientist James Q. Wilson. While the central focus of “Broken Windows” is the role of police in maintaining public safety, the piece also makes an impassioned argument for the idea that disorder begets further disorder — that “if a window in a building is broken and is left unrepaired, all of the rest of the windows will soon be broken.” Importantly, in their parable, the source of the broken windows does not derive from the existence of a large population of determined window-breakers, but rather to a small number of people who are emboldened by society’s disinterest in repairing the damage they have caused.

As Kelling and Wilson further argue, a broken window, left unrepaired, may have consequences beyond more broken windows. As they note, broken windows ultimately breed the social conditions under which crime flourishes: 

A stable neighborhood of families who care for their homes, mind each other's children and confidently frown on unwanted intruders can change, in a few years or even a few months, to an inhospitable and frightening jungle. A piece of property is abandoned, weeds grow up, a window is smashed. Adults stop scolding rowdy children; the children, emboldened, become more rowdy. Families move out, unattached adults move in. Teenagers gather in front of the corner store. The merchant asks them to move; they refuse. Fights occur. Litter accumulates. People start drinking in front of the grocery; in time, an inebriate slumps to the sidewalk and is allowed to sleep it off. Pedestrians are approached by panhandlers.

Implicit in this argument is that there are at least two ways to avoid a race to the bottom. The first, which inspired a generation of assertive policing, is that the police must deal with disorderly behavior before it escalates. The second, which has received far less attention in the 40 years since the article’s publication, is that broken windows should be fixed as quickly as possible, before the problem becomes worse. The latter implication is a central source of inspiration for CPTED-inspired approaches to crime control.  

Research offers abundant evidence that CPTED-inspired changes to the built environment can have important impacts on crime and violence. Does that mean that CPTED is the antidote to the rising violence that American cities have experienced since March 2020? Unfortunately, that would be far too simplistic a read of the literature. For one, most of the research has tested small-scale changes to the built environment. Whether those changes will continue to be effective when adopted at scale is an entirely different and completely unanswered question.  

A more reasonable takeaway from the literature is that CPTED-inspired strategies, traditionally seen as an exotic solution to fighting crime, have earned a seat at the table. Just as a diversified retirement portfolio will likely contain large, medium and small cap equities as well as bonds, a diversified crime-reduction portfolio should strengthen law enforcement as well as communities.  

Jane Jacobs did not believe in defunding the police, but she did recognize that police effectiveness is ultimately conditioned on developing strong communities where neighbors look out for neighbors and enhance police surveillance by providing their own “eyes on the street.” CPTED-inspired solutions, developed by those with local knowledge, offer a promising path forward in making public safety more organic and more sustainable.

Further Reading

Jacobs, Jane. The Death and Life of Great American Cities. New York: Random House,1961.

Wilson, James Q., and George L. Kelling. "Broken Windows." Atlantic Monthly 249, no3 (March 1982): 29-38.

MacDonald, John, Charles Branas and Robert Stokes. Changing Places: The Science and Art of the New Urban Planning. Princeton: Princeton University Press, 2019.