I guess it's because philly is a smaller city and not as densely populated
A lot of areas in Harlem and the Bronx are mostly tenaments and housing projects
You got a bunch of poor teenagers living on top of each other like that and fighting over drug territory among other things
It's only natural that they clique up
I doubt dudes are gang banging just for the sake of gang banging
And if they are they're probably not to be taken serious
Philly is densly populated right behind New York per sqaure mile we just have corners as our streets is smaller and everybody know each other. Philly on the other is very big on organizational crime such as mafia, black mafia, junior black mafia, bikers and black muslims/asians.
The cambodians tried that shyt here in philly years ago with that blood crip shyt and got their ass beat and left back for cali.
New York just surprised that it is picking up because it is so big