In the Franklin Reserve neighborhood of Elk Grove, California, south of Sacramento, the houses are nicer than those at Windy Ridge—many once sold for well over $500,000—but the phenomenon is the same. At the height of the boom, 10,000 new homes were built there in just four years. Now many are empty; renters of dubious character occupy others. Graffiti, broken windows, and other markers of decay have multiplied. Susan McDonald, president of the local residents’ association and an executive at a local bank, told the Associated Press, “There’s been gang activity. Things have really been changing, the last few years.