What Previous Studies Show
The following is a summary of the research literature on the relationship between migration and proliferation. Local law enforcement agencies have become increasingly aware of the usefulness of maintaining systematic information on gangs, yet such data bases hardly meet the scientific standards of reliability and validity. Therefore, the results of the studies described in this section should be viewed as exploratory.
Although a number of national studies dating back to the 1970's have documented an increase in the number of cities and smaller communities reporting street gang activity, the numbers reported by these studies vary (Miller, 1975, 1982; Needle and Stapleton, 1983; Spergel and Curry, 1990; Curry, Ball, and Fox, 1994; Klein, 1995; Curry, 1996). Variations in localities reporting gang activities are attributed to the use of different sampling frames in the national surveys. While the surveys are not compatible, each reports increased gang activity. Miller's 1996 compilation of data from several sources documents gang proliferation during the past three decades and shows that in the 1970's, street gangs existed in the United States in 201 cities and 70 counties (many with cities included in the former count) (Miller, 1996). These figures climbed to 468 and 247, respectively, during the 1980's and to 1,487 and 706 in the 1990's. A nationwide survey conducted by the National Youth Gang Center (NYGC) reported that in 1995 gangs existed in 1,492 cities and 515 counties (OJJDP, 1997). The figures reported by Miller and NYGC are considerably higher than the estimate of 760 jurisdictions reported by Curry and his associates (Curry, Ball, and Decker, 1996) and the projection of 1,200 gang cities derived from the 1992 USC national mail survey (reported in Maxson, Woods, and Klein, 1995). Similarly, the National Drug Intelligence Center (NDIC) reported a much smaller figure of 265 for cities and counties reporting gang activity in 1995 (NDIC, 1996). Of these 265 cities and counties, 182 jurisdictions reported gang "connections" to 234 other cities, but the nature of these relationships was not elaborated on (D. Mehall, NDIC, personal communication, August 20, 1996). With the exception of the Mehall report and that of Maxson, Woods, and Klein (1995), none of the studies addressed the issue of gang migration on a national scale.
With few exceptions, findings on gang migration reported in research literature contrast sharply with the perspectives presented by the media, government agencies, and law enforcement reports. Several researchers have studied gangs in various cities throughout the United States and examined their origin and relationships to gangs in larger cities (primarily Chicago) to examine correlations between gang migration and proliferation on a more regional scale.