A criminal justice professor in Chicago has hit on a key factor to reduce the murder rate: provide affordable housing:

A study of the city's murder rate shows an unlikely factor at the heart of the violence. Chicago's rate is three times that of New York not because of policing, but because of a lack of good, affordable housing.

Here's some of what John M. Hagedorn, associate professor of criminal justice at the University of Illinois-Chicago and a senior research fellow at the Great Cities Institute, has to say:

I'm in the midst of a two-year study, funded by the Harry Frank Guggenheim Foundation, to investigate why Chicago's homicide rate hasn't fallen like New York City's. While we are still collecting data, Mayor Richard Daley's recent call for ideas to stop the violence has convinced me to join the discussion now.

Hagerdorn doesn't buy that policing styles make the difference since murder rates have also dropped in Boston, Houston, San Francisco and San Diego, without a Rudy Giuliani or Bill Bratton. He notes that violence "is generally high in cities and areas that have undergone severe disruption of daily life."

In Eastern Europe. Albania, for example, according to the World Bank, has very high rates of violence, and a quarter of all of its young men are working in the drug trade. Wherever there are cities with desperate conditions and high rates of violence, as in Kingston, Jamaica, Rio de Janeiro, Brazil, or Bombay, we also find groups of armed young men. Whether they are paramilitaries, drug cartels, death squads, militant fundamentalists or gangs, these groups are a major obstacle to stopping the cycle of violence.

It is also apparent that where class differences within dominant groups is the main source of conflict, violence is usually sporadic and muted. High rates of persisting violence are almost always related to ethnic, racial or religious conflict.

The wide variation in rates of violence within ethnic groups debunks any notion that African-Americans, or Irish, or Hispanics are violence prone. Violence is a property of social structure, not people. (emphasis supplied)

Turning to Chicago, Hagerdorn says,