March 5, 2013
Using zoning laws to shape the type of development and activity that occur in a neighborhood may be one way to reduce crime in urban areas, according to a new RAND Corporation study.
Studying high-crime areas in the city of Los Angeles, researchers found that city blocks that included both residential and commercial zoning purposes experienced less crime than nearby blocks zoned primarily for commercial purposes. Crime was lowest in blocks zoned for residential-only uses, even in relatively high crime neighborhoods.
The study found that single-use commercially zoned blocks in Los Angeles have crime rates that are 45 percent higher than similar blocks that include residential uses.
“At least in the case of a city like Los Angeles, zoning matters—an important fraction of reported crime is associated with the kind of zoning on a city block,” said James M. Anderson, the study's lead author and a behavioral scientist at RAND, a nonprofit research organization. “These results suggest both researchers and policymakers should pay more attention to the ways in which zoning and other land-use policies can affect crime.”
Policymakers have long debated the effect that city planning and zoning can have on crime. Some experts have urged diverse uses of land in order to create an urban environment that encourages “eyes on the street” to deter crime.
But there has been relatively little objective research designed to test these theories and most of the studies that have occurred have focused on older cities in the eastern United States.
The study by Anderson, co-principal investigator John MacDonald of the University of Pennsylvania and colleagues uses stronger scientific methods than previous studies and focuses on a younger city—Los Angeles—that has land-use patterns that are more typical of where urban growth is occurring today. The results are published in the February edition of the University of Pennsylvania Law Review.
Researchers examined the relationship between land-use law, the built environment and crime using detailed block-level crime information from July 2010 to January 2011 and detailed observations about 205 blocks in eight relatively high-crime areas in Los Angeles. In addition, researchers conducted a separate analysis of the relationship between changes in land-use zoning and crime in all neighborhoods in Los Angeles from 1994 to 2010.
The central finding of the study is that blocks in the study area that include both residential and commercial zoning uses experienced less crime than blocks that are zoned for primarily commercial purposes.
Overall, crime was lowest on blocks zoned for residential-only uses, even in relatively high crime neighborhoods. Researchers say the finding suggests that efforts to reduce crime by introducing commercial activities in residential areas are probably misguided.
The study also found that when neighborhoods throughout Los Angeles undergo some change in zoning, mostly toward residential uses, crime drops more than it does in neighborhoods with comparable crime trends before the zoning change. In these cases, crime dropped by about 7 percent on average, mostly as a result of fewer automobile-related property crimes.
This finding is consistent with the apparent crime-reducing effects of residential development that was found in the first study, researchers say.
“Our findings suggest that strategic decisions about zoning could be part of the overall crime prevention strategy in urban areas,” MacDonald said. “However, our findings are based on one city and should be replicated by additional studies.”
Researchers suggest it would be good to test the study's conclusions with a small-scale experiment in which a limited set of proposed zoning changes could be permitted randomly to see if the benefits of zoning changes reduce crime in neighborhoods.
The city blocks examined in the study were drawn from the communities of Boyle Heights, Highland Park, Hollywood, San Pedro, South Los Angeles, Southeast Los Angeles, West Adams and Westlake.
Support for the study was provided by the Robert Wood Johnson Foundation's Public Health Law Research program. Other authors of the study are Ricky Bluthenthal of the University of Southern California and J. Scott Ashwood of RAND.
The project was conducted within the RAND Safety and Justice Program, which conducts public policy research on corrections, policing, public safety and occupational safety.