They are stripped of their contents and their signs, replaced by For Rent banners that can be seen along entire stretches of otherwise thriving shopping zones.

“When you walk the streets, you see vacancies on every block in all five boroughs, rich or poor areas — even on Madison Avenue, where you used to have to fight to get space,” said Faith Hope Consolo, head of retail leasing for Douglas Elliman Real Estate, who said the increase in storefront vacancies in New York City had created “the most challenging retail landscape in my 25 years in real estate.”

A survey conducted by Douglas Elliman found that about 20 percent of all retail space in Manhattan is currently vacant, she said, compared with roughly 7 percent in 2016.

While a commercial crisis might more likely be associated with periods of economic distress, this one comes during an era of soaring prosperity, in a city teeming with tourism and booming with development.

That has aggravated the vacancy problem by producing a glut of new commercial real estate.