Anyone who's spent time answering the newsroom phone has heard from them - the people who live next door to the house with the falling-down garage or the giant trash pile or the rodent den. One at a time, the sad tales don't amount to much - maybe a news feature on a slow day. But start digging around in your city's housing inspections data, then plot what you find on a map, and the story gets better.

At the St. Paul Pioneer Press, one of our city hall reporters, Charles Laszewski, wanted to investigate complaints that the housing inspections chief wasn't tough enough on owners of run-down properties. So we asked for the city's housing inspections database. We defined a problem property as one with repeated violations spanning two years or more. Then we turned to our mapping software. Our inspections data listed the street address for every property inspectors visited.

We wanted a map showing the rate of problem properties per 1,000 housing units. Our efforts resulted in uncovering neighborhoods where one of every three houses had chronic housing code violations. The series brought about some results: The City Council added money to the budget to hire more housing inspectors. The mayor announced a police sweep to arrest property owners with outstanding housing court warrants.

And the county is spending more money to maintain tax-forfeited properties.