What would it take to build a city that mirrors the auto manufacturing capabilities of Detroit in its classic car period? Note that this isn't Ford, or GM that

What would it take to build a city that mirrors the auto manufacturing capabilities of Detroit in its classic car period? Note that this isn't Ford, or GM that did it.. but rather Ford and GM and hundreds of smaller companies that supplied the raw materials to a company to make the parts that were used by companies that supplied the parts to the auto makers. And so, yes, you could - but its not something that one company can do - or for that mater even has the competency to do for the same reason that Ford doesn't run steel mills.