I do not think that San Francisco can in any way be compared to the decline of Detroit.<p>Poor civic planning, racism and the loss of jobs to non-union Southern plants all paid a part in Detroit&#x27;s population dropping by two thirds over a fifty year span.<p>I read a great book over Christmas, Once in a great city by David Maraniss, which covered Detroit at its peak from 1962-1964.  Wayne State actually pretty accurately predicted the city&#x27;s future then but the report was ignored by those in a position to stem its decline.