In the current issue of the New Republic (not yet online) Noam Scheiber writes that Newark mayor Cory Booker's commitment to alleviating poverty is probably quite genuine. Then this:
On top of which, Booker has been a pretty good mayor. Violent crime in Newark, while still a scourge, has declined on his watch, notwithstanding a brutal recession.
You already know what's coming next, don't you? Here's violent crime in Newark:
I don't have an axe to grind either for or against Booker, but it sure doesn't look to me like violent crime has declined on his watch. It declined from 1995 through 2007, most likely thanks to the phaseout of leaded gasoline. Also: it's a bit of an urban myth that crime increases during recessions. There's actually not much of a correlation.