PORTLAND, Maine — There is nothing obviously wrong with Maine’s biggest city. Its shops buzz in the summer with well-heeled tourists. Zillow rates the real estate market “very hot.” David Geffen’s yacht docks at port from time to time. The food scene is great. In November, the unemployment rate was barely 2.2 percent.

Something is troubling Portland, however. Productivity growth is low. Business formation is anemic. And there is a sense that in an era of technology-driven economic winners, Portland’s 66,000 residents are being left behind. Read more