Deaths from homicide are a major public health problem in the United States and throughout the world. Further, the United States has experienced homicide rates that are 6.9 times higher than those in other high-income countries, and the vast majority are attributable to firearms.1 For many decades there have been striking regional variations among various cities throughout the United States in deaths from homicide, and size is a major determinant.2 In addition, there has been considerable publicity about high rates of homicide in some major cities like Chicago and low rates in others like New York City.