I don't know this, but let's suppose that by your use of this term "exercise of economic power", you imply some moral sense in which the action is unrighteous or unjust. Right? (Bear in mind that, of course, from the opposite perspective, it sounds a lot like "blaming the victim.")
Consider a not hugely dissimilar migration that happened around the same time: the migration of French Algerians to metropolitan France. Here's a short Wikipedia page:
https://en.wikipedia.org/wiki/Oran_massacre_of_1962
Totally serious, non-rhetorical question: would you categorize this historical event as "exercise of economic power" or as "ethnic cleansing?"
Also, is there any generalization that can be drawn across the political systems in which these two events happened (decline of Detroit, independence of Algeria)? Or is it just a coincidence that they both go down in the '60s?