Since the mid-1990s, there has been steady drumbeat about US cities "bouncing back". This is, of course, unlikely but, nevertheless, provocative because turnarounds are big news.
I now have my 2003 US Statistical Abstract CD ROM (much handier than the hard copy) and here are the population shares since 1990 for New York city, for the top-20 cities and for the top-75:
PLACE(S) 1900 1940 2000
New York city 4.52% 5.65% 2.84%
Top 20 cities 15.73 18.97 10.96
Top 75 cities 22.03 27.42 18.24
Cities as interesting units of analysis have been eclipsed by metro areas and their exurban hinterlands. Nevertheless, Smart-Growthers, big-city politicians and their acolytes have been selling a fable to gullible media.
The cities, as we knew them, peaked near about 1940. There has been no turning back. For many years, national politicians worried over being seen as not having an "urban policy", e.g. pumping enough tax money into declining areas. The welfare policy that seemed to matter was all about places and not people. As people do better, they leave declining places behind. Political representatives, however, represent places, not people.