Free trade and offshoring killed Detroit.
Actually the election of Coleman Young as Mayor killed Detroit.
It delivered a very clear signal to whites that “You are not welcome here. I am going to do everything in my power to take revenge on you.”
They began fleeing in droves. Creating a city in which blacks ultimately did not want to live either.
The decline of the auto industry has a lot to do with foreign competition.
The success of foreign competition has a lot to do with globalization-related factors, but also a great deal to do with the quality of the cars produced in Detroit and the slowness of our auto industry to innovate in response to foreign competition.
BTW the population of Detroit in 1850 was only 21,019.