I knew relatives who lived in and around Canarsie (Brooklyn) in the 40's --there were more Euro-immigrants there than now. One died from a robber slitting veins in his arms, the other from a stabbing (by strangers in both cases). So it seems to have been a voilent city for much of its history, not just something which came after the WWII boom subsided and sliding into the socio-economic issues of the 60s and 70s.
I'm glad to see the city enter a new era of relative peacefulness. Now, I'd like to see the infrastructure upgraded to befit a great modern metropolis.