No they didn't, they expanded into the suburbs.....
I can give you the Chrysler Jefferson Ave. Assy. plant, Mound Rd. Engine plant, Lynch Rd......etc. as examples.
Its kind of interesting if you look at perceptions vs realities. (I’ve been looking at birdseye veiws of the packard plant this morning)
The Packard plant is shown as the worst of the worst covering a vast area but its tiny compared to the Cadillac assembly plant across the highway. The Packard property is long and narrow, 1 to 2 blocks wide by several blocks long. You could never build a factory like that today. There are working businesses around it and it looks like many of them use the place for parking trailers and dumping trash.
The architectural firm recently hired to look at the place says that 85% of the buildings are structurally sound due to the fact that it was built perfectly suited to the Michigan environment.
Out of the TOTAL number of automotive plants that USED to be in Detroit, those few are a drop in the bucket.