This isn't quite true for many of the big cities of interest. There was an active high-modernist effort in the ~70s to destroy the walkable, transitable, livable parts of many American cities and cut freeways across them like big ugly neighborhood-destroying scars.
Even transit wastelands like LA had an actual urban core (that they're now rebuilding), as well as a relatively extensive network of streetcars.
Even transit wastelands like LA had an actual urban core (that they're now rebuilding), as well as a relatively extensive network of streetcars.