The study found that an average of 2 per cent of youth in the US are gang members, with involvement highest at age 14, when about 5 per cent of youth are in gangs.
Youth in gangs also come from all types of backgrounds, researchers said.
"The public has been led to believe that gang members are black and Latino males and that once someone joins a gang they cannot leave a gang, both of which are patently false," said David Pyrooz, assistant professor of Criminal Justice at Sam Houston State University.
The authors of the study looked at the number of gang members, the characteristics of youth in gangs, and how many youth join and leave gangs each year in the US.
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They analysed questions about gang membership that were included in the National Longitudinal Survey of Youth 1997, nationally representative data collected by the US Bureau of Labour Statistics.
The researchers found that gangs have high turnover rates of 36 per cent, with about 400,000 youth joining gangs and another 400,000 youth leaving gangs every year.
Law enforcement severely undercounts juvenile gang members, with national estimates at 300,000, less than one-third of what was found in the study, researchers said.
The reason, Pyrooz said, is because "law enforcement uses a top-down strategy, recording older and more criminally-involved youth as gang members, which ignores younger and more peripherally gang-involved youth, all of whom are captured in the bottom-up strategy we use in this study."
Since gang membership has so many negative health and life outcomes, even after someone leaves a gang, relying on law enforcement gang data alone would under-diagnose problems youth violence and ways to respond to it, researchers said.