Here’s an interesting story about crime in Memphis, Tennessee, and how it’s been changing over the past few years. Richard Janikowski is a criminologist with the University of Memphis, and he’s been working closely with the Memphis Police to figure out what was happening.

The inner city, where crime used to be concentrated, was now clean. But everywhere else looked much worse: arrests had skyrocketed along two corridors north and west of the central city [...] and along one in the southeast. Hot spots had proliferated since the mid-1990s, and little islands of crime had sprung up where none had existed before, dotting the map all around the city.

Why was crime happening in random spots around town, in the areas farther out, not in the inner city area?

Janikowski might not have managed to pinpoint the cause of this pattern if he hadn’t been married to Phyllis Betts, a housing expert at the University of Memphis [...] Betts had been evaluating the impact of one of the city government’s most ambitious initiatives: the demolition of the city’s public-housing projects, as part of a nationwide experiment to free the poor from the destructive effects of concentrated poverty. Memphis demolished its first project in 1997. The city gave former residents federal “Section8″ rent-subsidy vouchers and encouraged them to move out to new neighborhoods. Two more waves of demolition followed over the next nine years, dispersing tens of thousands of poor people into the wider metro community [...] Over time, she and Janikowski realized that they were doing their fieldwork in the same neighborhoods.

Which is to say, crime was happening where all the Section8 residents were living. It was not the kind of thing anyone wanted to talk about.

Betts remembers her discomfort as she looked at the map. The couple had been musing about the connection for months, but they were amazed-and deflated-to see how perfectly the two data sets fit together. She knew right away that this would be a “hard thing to say or write.” Nobody in the antipoverty community and nobody in city leadership was going to welcome the news that the noble experiment that they’d been engaged in for the past decade had been bringing the city down, in ways they’d never expected.

It’s a typical story of how the good intentions of government programs lead to whole worlds of consequence.