The NACJD aims to facilitate research in criminal justice and criminology through the preservation, enhancement, and sharing of computerized data resources, through the production of original research based on archived data, and through specialized training workshops in quantitative analysis of crime and justice data. This could be helpful in peripheral data on violent crimes related to gangs.
Put out by the U.S. Justice department, this resource offers ways that the federal government addresses the problem of gangs and how to prevent youth from criminal activity. This page is on the Comprehensive Anti-Gang Initiative.
An organization that provides resources for victims of crime. Contains a lengthy report on youth gangs in America called "Snitches Get Stitches: Youth, Gangs, and Witness Intimidation in Massachusetts" with statistics.