Low income and high population density. It seems that crime rates grow faster than the population density rather than at the same rate, so an area with twice the density of another area, but the same average income, might have a crime rate that is three or four times that of the less dense area. On top of this, areas that are populated mostly by minorities also tend to have gang problems. So a small percentage of the population that lives there are doing the bulk of the serious crimes.

So why are the "low income areas" basically all black? Coincidence?

You basically just agreed with what I said. Other than a few MCs, most of which remain pretty small when compared to other gangs, poor white areas don't suffer the gang problems that poor black and Latino areas suffer. However, if you really look into, many of the black gangs that exist today can trace their roots back to the civil rights movement. They were originally created as a way for minority neighborhoods to both police themselves and protect themselves from the corrupt white police. The problem here is that they didn't just disappear when the movement ended and their views got twisted and corrupted, they sometimes split into smaller gangs based on disagreements and then started killing each other over turf and money as well as robbing, selling drugs and killing anyone that got in their way or just happened to be around them when **** got bad. Having said all that, I think that if we could manage to take care of the gang problems, which isn't going to happen with the budgets a lot of the worst cities give to their police departments and all the protests, we would see a dramatic drop in black and Latino crime rates, possibly enough to be in line with white crime rates.

well if you built a decent school system that allowed them to get out of poverty, would that not solve much of the problem?

What about war vets?