“For lease” signs all but define every block in some neighborhoods, rich as well as poor. Take the Upper West Side. Its City Council member, Helen Rosenthal, reports that her staff recently surveyed shops along Broadway and Amsterdam and Columbus Avenues, and on some side streets. Of 1,332 storefronts, 161, or 12 percent, were unoccupied. The situation, Ms. Rosenthal correctly says, is a threat to the area’s character, its “sense of community” and even its residents’ sense of safety. While a comparable citywide census of empty storefronts is needed, the Upper West Side is obviously not alone.

On one level, there’s just so much the city can do. Online shopping is here to stay, and it takes an inevitable toll on brick-and-mortar stores.

But landlords can be blamed mightily for this blight — the greedy among them who raise rents to stratospheric levels, figuring that some deep-pocketed company will pay top dollar for the space. Speculative behavior has led to boom-or-bust cycles, as on Bleecker Street in Greenwich Village. It was fancy boutique heaven for a while. But how many $400 T-shirts does even the wealthiest New Yorker need? Boutique heaven turned into vacancy hell.