The point of the article is to normalize that "americans" is synonymous with "urban new yorkers" and the rest of the population doesn't count. Clearly, rural mining ghost towns are familiar with the concept of slowly shutting down a boomtown. See also the rust belt cities which were de-industrialized about three generations ago, and continue a slow decline, or at least slower growth than the rest of the country, sinc…
Quick question where do you think the huge population growth in large cities over the last few decades came from? Cities are full of people who lived through part of those declines and left, or grew up in those places after and left. Part of what "decline" means in this context is "your young and ambitious people all left for the nearest very large city or NYC."
San Francisco was exponential growth until 1940, then flatlined since 1950.
Detroit and Baltimore were those destination cities until 1970 or so.
Huge population growth in large cities is a pre-WWII effect and its an outside the US effect.
Last time NYC had Shenzhen-like population growth was over a century ago.