A storeowner who grew up in Portland told me this area of abandoned railroad warehouses used to be the most run-down, crime-ridden and dangerous neighborhood in the city. You wouldn’t know it now.

On a summer night, the Pearl District hosts a scene that is the envy of urban planners around the world – stores, galleries, sidewalk restaurants, sleek new condo and apartment buildings, kids playing in Jamison Park, people just out for a stroll.

In what locals call “the Pearl,” you can shop at the legendary Powell’s City of Books and then walk a couple of blocks to a Whole Foods gourmet grocery store. As often happens in Portland’s rejuvenated neighborhoods, the store occupies the first two floors of a building where people live.

So why is Portland so successful in reinventing neighborhoods? My Sunday column – here – seeks to find a few answers.