Some of the earliest efforts to understand these social units have been the extensive descriptions of urban street gangs in the 1920s and 1930s, continuing through the 1950s, which understood them to be largely reactions to the established authority. The primary goal of gang members was to defend gang territory, and to define and maintain the dominance structure within the gang. There remains in the popular media and urban law enforcement agencies an avid interest in gangs, reflected in daily headlines which emphasize the criminal aspects of gang behavior. However, these studies and the continued interest have not improved the capacity to influence gang behavior or to reduce gang related violence.