Detroit's mistake was "over-investing" in automobile manufacturing, even after it became clear that process could easily be out-sourced or off-shored. If hindsight was 20/20, they wouldn't have relied so heavily on that one industry, or built cities and suburbs totally dependent on it. If they had merged their industrial power with Chicago's financial power when it mattered....the "center of the financial universe" might have grown in the heartland, instead of NYC and the east coast.