“I believe there’s only so much the police can do about this,” Sun-Times columnist Mark Brown observes today, about the rise in murders in Chicago this year. “What we’re seeing is the result of an economic and social breakdown in poor neighborhoods, not inadequate policing.”

Brown’s right—although calling it a “breakdown” makes it sound like something new. For more than 40 years now, the city’s murder rate has waxed and waned under various mayors and police superintendents, but it’s always been exponentially higher in Chicago’s poor neighborhoods.

This isn’t, mainly, because poor neighborhoods lack sufficient police protection. It’s because concentrated urban poverty nurtures violence. It always has and always will.