Dave,
GM's Hamtramck Plant (Hamtramck is a city entirely surrounded by Detroit, as is Highland Park) is what I had in mind when I mentioned them as having some Detroit operations along with Chrysler. The GM Hamtramck plant was built on the grounds of Chrysler's old Dodge Main factory (and a few Hamtramck neighborhoods) in 1981. It began producing GM's downsized 80s Cadillacs that were never very popular, but eventually moved onto the better received Seville/STS platforms. It now builds the Volt hybrid, and some overflow production of the Malibu I believe.
The 94-year-old GM/Chevrolet axle plant in Hamtramck was sold to a new company called American Axle. The owner Richard "dick" Dauch bought the plant in 1994, and made quite a fortune, allowing him to build a new plant in Michigan, then Mexico. The Hamtramck workers took a roughly 40% pay cut in 2008, then Dauch demanded cuts from $18 to $11 per hour. That was the end, and the plant closed. It's scheduled to be demolished. Dauch is dead now, and most people like it that way.
Chrysler left Highland Park as its engineering headquarters beginning in 1991 and completed the move to Auburn Hills (30 miles north on I-75) by 1994. One of the reasons was that the surrounding HP neighborhood was so unsafe it was becoming impossible to recruit engineering talent. This was the same reason Chrysler's Jeep/Truck engineering left Detroit around 2007.
One of the things that always astounds me as both a student & participant in Detroit & Automotive history (as well as an elected suburban politician!) is that as much as you might expect Detroit (and Hamtramck/Highland Park) city government to kiss the asses of its MAJOR automotive tax payers; it's almost the exact opposite. These big manufacturing/engineering centers are hugely capital intensive, so moves aren't done lightly. As a local government, you have to screw-up for a very long time, in very bad ways to convince them to move... It's not like leaving your 1000 sq. foot bungalow.
The remaining auto plants are like mini cities within the city, with their own powerhouses, water treatment plants, security, etc. On three shifts they might employ 5,000 people who make (and spend) a great deal of money. Rather than marshalling resources around them... Police presence, code enforcement, new development, etc. the leaders of the city of Detroit (one Mayor, from '74-'94) instead pursued get-rich-quick schemes for casinos and mass-transit boondoggles downtown and along the riverfront throughout the 80s and 2000s. I suppose new development in these areas offered the best opportunities for graft; as opposed to simply protecting what already existed.
I work at a very small facility which is "technically" within the city of Detroit, but is literally a few hundred feet from a suburban border. We moved our operations from another Detroit facility. Our former plant was completely rebuilt at a cost of several hundred million dollars, and re-purposed into an engine plant. GM & Chrysler have moved many things from Detroit, but they have also re-invested many times over. When we moved in 1996, our surrounding neighborhood was one of the aforementioned "copper canyons" of Detroit police/fire/DPW workers. As a result, the neighborhood was still quite attractive, safe and readily mortgagable. Since I didn't need the schools as a single man back then, it would have been reasonable for me to even consider buying a 1950s-brick home nearby, but a 3% additional income tax for then-marginal city services was not encouraging.
When city workers were allowed to reside elsewhere in 2001, changes in the neighborhood which had been slow, began to accelerate like someone added gasoline to a fire (pardon the pun). Suddenly you began to see stolen cars dumped on the streets. At first they would be towed away within a day. Then they began to sit for weeks. Eventually they'd sit until they were set on fire for "fun" by the newest residents in the neighborhoods. Services went from marginal to non-existent. Trash used to be seen only on the day before pick up. Now it was "socially acceptable" to throw your old couch out in front a week before pickup. When Detroit cut its large item trash collection from weekly to monthly (to save $$), couches and other garbage began to sit on lawns for a month. Many of the newest homeowners came from government housing projects and had no experience with strange ideas like cutting the grass or fixing a downed piece of siding. With so much overgrown grass and garbage (and rats under the piles) people stopped using sidewalks and walked en mass in the streets; defying cars to go around them. Laws about business signage we ignored. First it was mild violations like covering the windows with liquor and cigarette ads, then it was painting the entire building neon-pink to attract attention. When that provided inadequate, the business was burned for the insurance money.
Now this neighborhood which would have been might have been seen as "a little quirky, but safe" for me to move into circa 1996 looks like zombie-land in 2013. I drive in with high-beams on because none of the street lights work. For some reason, there are more people walking in the streets at 4:30 AM than 6 AM (my start time is flexible). Some of the houses have been burned, probably to squeeze out those last few dollars of insurance money. The burned houses become even larger dumping grounds for old tires, (appliances!) furniture, etc.
This could have been stopped cold in 1996 had Detroit leadership had the brains to say "Hey, there's a Chrysler facility with 150 well-paid workers in the area of Van Dyke/Outer Drive; let's tighten up on code enforcement, forfeiture, and police patrols. Let's ticket people who dump couches on their lawns and don't cut the grass. If they don't pay their tax bills, we take the damn house. Let's run police cars up and down Conner Avenue so often nobody would dare dump a stolen car. Make sure the DPW keeps the street lights on, etc. etc." After all, by 1996 older, wider swaths of the city had already fallen into ruin. Most of the area I work in was built in the 50s/early 60s, just like the surrounding and stable suburbs.
Now my facility has the same attractive mid-century-modern (built 1966) facade and trimmed green lawn & trees it did in 1996; but it's surrounded by a 6' wrought iron fence because they were tired of replacing computers from broken office windows and having cars stolen from the lot. How much longer do we put up with this?
Detroit's mayor and council attitude towards their major employers was the same one they gave their middle-class African-American constituents... "Hehe, they'll never leave!" Well I'd say the joke was on them; except the worst political offenders are either dead by now, or in jail.
This is a viewpoint you're not likely to hear in the mainstream media because speaking poorly of Detroit's post-'67 riot politicians is not considered "politically correct". Ironically, it IS politically correct to blame manufacturing; who although they have moved in some cases, the remaining factories are generally islands of cut green lawns and maintenance in a land of jungle-like grasslands and burned structures. Of course, nice buildings aren't as interesting to look at as long-abandoned car factories, so there is a perception that there is "nothing" left in Detroit. The truth is it is very bad, but there are salvageable areas. I'm no fan of our current state government, but with the collapse of the utterly criminal Detroit political structure's power, I am hopeful that some (besides the largest industrial companies) will be willing to again consider investment in Detroit.
