I would also add that cities with growing populations seem to buck the crime trends - declining cities like Detroit, Chicago, Cleveland, Baltimore, Philadelphia seem to become increasingly violent.
To be declining, doesn't that mean that people are leaving? Who are leaving and why? Welfare checks are mailed to wherever you are, whereas paychecks are sent only to where the job is. Those who leave to find work leave behind the jackals who prey upon whoever remains. IOW, the proportion to crims to vics increases as the "good people" leave.
An interesting study is Memphis - for a while there it seemed to be growing, but over the past few years population has dipped to 1980 levels while violent crime has dipped somewhat as well.
That would seem to correlate well to the CRUSH program implemented in Memphis a few years ago. Prediction: text messages run through a CRUSH similar program will be the tool law enforcement uses to deal with flash mobs and other bozos who use wireless technologies to advertise their future crimes.
Places like Harlem, Flatbush, Springfield Gardens, Fort Greene (and others) are proud of their successes and their resilience. There are still problems in these areas but they are not of epidemic scale.
Additionally, NYC is a global destination for anybody and everybody, including Black Americans from other areas. These foreign and domestic immigrants are here to work, they don't have time for the bullshit. I don't think that is true of other US cities.
There is no doubt that crime is on the rise but we still have a long way to go to sink to the levels of the mid 70s through the mid 80s....those days were undeniably flat-out dangerous.