In the summer of 2006, Dorothy Wiley and her husband, Charles, moved into a tidy three-bedroom house with peach siding and navy-blue trim in Shreveport, Louisiana.

They’d grown up in Shreveport but had been living in New Orleans when Hurricane Katrina hit. After being trapped in the Superdome for a terror-filled week, Wiley was determined to make a fresh start, and she joined a tide of evacuees heading north to Shreveport, where she’d grown up. Resettling there with family, she heard about a national nonprofit building homes for Katrina evacuees in a neighborhood called Allendale, just west of downtown.