Actually I'd like to point out that "blacks" as you put it don't necessarily segregate on racial lines as the bloods and crips had both white and black members and we had both of them up here for a while.

If you're unsure of your gang names or info you can always google it, I was unfortunate enough to grow up in my view and knew kids in high school at West, Dimond and East respectively who were involved in gangs during that time period.  

Just a point.  Whites are happy to join up like anyone else, I think much has to do with prevailing poverty and abuse at home.