How did the economy of Detroit have a downturn with the collapse of the automobile industry?

I live in Detroit, and my father worked for one of the big 3 auto company's. In Detroit a lot of people find work in the automotive industry. When everything went down hill there were mass amounts of lay offs, and to my understanding it was a ripple affect. All the people who worked for the automotive industry did not have the money to go out to eat, or buy things they once bought, so the surrounding businesses fell after them. There are a lot of people who have gone back to school to get out of the automotive industry as well as a lot of people who moved out of state. Detroit lost a lot of population in the 2010 census. I do not think that Japans Auto industry was a main factor in the collapse of Detroit's industry. The engineers working for the auto industry had been in there for a while, some like my dad for 26 years, had just been getting paid more and more money, and eventually the company's could not afford to pay all of their employees, thus causing the lay-offs. Like I said I think it really had a lot to do with the fact that so many people lost their jobs working for these company's. I by no means know that these are the actual facts or reasons, but I did live through it all, so hopefully it points you in the right direction.