There have been much arguments about crime in the United States. Regardless, one thing everyone agrees on is that low income is highly correlated with crime. The areas hit the worst by crime are usually areas with Section 8 housing. This is government assisted housing, and it is often populated by individuals with no intention of getting out of it, and thus leeches off Government money.
Those who actually have to rely on section 8 due to unfortunate circumstances do not stay for long, as they eventually find their way out of the situation. The people residing here often do not have jobs (by choice), and thus have all the free time they need to get into drama and altercations.