What happens when cities tear down public housing? The issue has played out in Baltimore and major cities across the country (remember the controversy surrounding HOPE VI, or Opportunities for People Everywhere? More here on that).

A new study out this month by the Urban Institute and Emory University reveals the latest on the subject. It's an attempt to answer with "empirical evidence" whether a common perception is true: that teardowns contribute to crime waves in the neighborhoods where the former public-housing families settle.

It's not a simple answer, the authors conclude. They looked at effects in Chicago and Atlanta.

"Crime declined dramatically in both cities throughout the 2000s—even in neighborhoods that received many relocated households," they write. However, "the picture is not entirely positive."

"The transformation contributed to slightly higher property crime overall in Chicago, and some neighborhoods in both cities have experienced problems associated with concentrations of relocated households. Once the number of relocated households reached a certain threshold, crime rates, on average, decreased less than they would have if there had been no former public housing inmovers."

Chicago Housing Authority’s Plan for Transformation relocated some 6,400 families between 1999 and 2008 from public housing to private homes. In Atlanta, about 10,000 families were relocated from 1996 to 2011.

Relocating the public housing residents in Chicago is credited with decreasing overall violent crime by 1 percent and a 4.4 percent drop in gun crimes between 2000 and 2008. In Atlanta, the relocation efforts are credited with dropping violent crime by 0.7 percent between 2002 and 2009.

The impact on the neighborhoods with the demolished public housing was substantial, especially in Chicago: Violent crime plummeted more than 60 percent and property crime dropped nearly 50 percent, according to the study.

Relocation efforts had basically no impact on neighborhoods where the number of relocated families was low, the authors found. But in the "relatively small number" of areas with a concentration of relocated families, there was a ripple effect.

A neighborhood with a moderate concentration of relocated families “had a violent crime rate 11 percent higher in Atlanta and 13 percent higher in Chicago than it would have had with no relocated households,” the report found. Neighborhoods with high concentrations had violent crime rates "21 percent higher, on average, than they would have been with no relocated households, other things being equal."

"Our findings clearly indicate a much smaller impact of public housing transformation on
destination neighborhood crime rates than popular accounts imply," the authors write. "Nevertheless, they suggest that there are negative impacts for some neighborhoods when relocated households take up residence in them."

The study also notes that the neighborhoods where most of the former public housing residents relocated were vulnerable to start, because of existing crime, poverty and unemployment. 

"In other words, our story is not the popular version of previously stable communities spiraling into decline because of public housing residents moving in, but rather a story of poor families moving into areas that were already struggling," the authors write.

Relocating families may bring crime with them. The flip side is that they may themselves be at risk for becoming victims of crime thanks to the disruption to their social network as a result of the move, according to the report.

(The authors add that families using housing vouchers who hadn't been relocated from public housing "have much smaller effects on crime rates than relocated households, and it takes a much higher density of traditional voucher holders before we see any effect at all.")

Susan Popkin, the project’s lead investigator and director of the Urban Institute’s Program on Neighborhoods and Youth Development, said the biggest policy implication that is illustrated by the research is a need for “responsible relocation strategies.”

The policies need to “offer former residents a real choice of housing and neighborhoods, and provide long-term support to them once they leave public housing,” Popkin said. “Housing authorities planning large-scale redevelopment should learn from the experiences of these two cities about how to support former residents in moving to a wider range of communities and not creating new concentrations of poverty in other vulnerable neighborhoods.”

Housing authorities can help to ensure the developing communities are stabilized by providing support services before and after the families move, the authors say. They also suggest financial incentives for landlords in safe areas.

To read more on the subject, check out this article from Chicago magazine.