The democrats do several things....they under fund, under staff and then undermine the police...you are seeing that now in Chicago and New York in particular....they allow the education wing of the democrat party to run inner city schools...because they are pro union over pro education...so their graduation rates stay low...in Chicago...only 50 % of the kids are graduating from high school, and of those who graduate they poorly educated, they then tax, fine and fee businesses...since democrats think that all money belongs to the government, they drive good businesses out of the cities and they take good jobs with them....as is happening in Chicago and Illinois...they increase welfare and create a dependent voting class...they get a subsistence living if they vote for democrats...but not much else....
There aren't enough police to protect the whole city properly, so the rich, white democrat areas get protection, the democrat minority voters get poor to no coverage. The welfare and education policies of the democrats create generation after generation of single mother homes, where children are raising children with no adult role models.....this was best summarized by LBJ and how the Great Society would keep blacks voting for democrats for 200 years......and it worked....
So young, teenage males, raised by single mothers and mentored by gang members and drug dealers, have learned to solve problems with violence and crime.....and as long as the rich, white democrats are protected from them....and they keep voting for democrats...they see no need to help them change their situation....
Notice....New York had been a crap hole for decades under democrat mayors.....along comes Republican Guiliani.....and he cleaned the place up....now....democrat (bloomberg is a democrat) after democrat...you see the city starting to go back to the bad old days.......