I still don't follow. Detroit's configuration was much more like NYC's or Chicago's than Los Angeles. Frankly, Chicago is Detroit's closest cousin in terms of major cities. The density and build of Chicago more closely resembles Detroit than it does New York, and it's pretty much always been that.
According to a recent Freep editorial, in 1970 Detroit still accounted for more than 40% of the regions jobs, compared to today where it accounts for less than 13%:
The article is no longer on the Freep's website, but can be read here:
http://insurancenewsnet.com/article....type=newswires
Industrial jobs were clustered in and around southwest Detroit, corporate and clerical downtown, and service jobs in the commercial centers.