The only book that has covered Detroit is
Target: UCAS, which has a 22-page chapter on Motor City. You can find a copy
here.
There are a couple of follow-up paragraphs (and by "a couple" I mean two paragraphs, and the shadowtalk is actually longer) in
Shadows of North America. The only thing of note is Miss Tick's* comment about them building a wall around the metroplex and covering it with a biomass net.
Sixth World Almanac says the wall went up, but the net did not survive initial contact with the rest of the board. Detroit also had 2% unemployment in 2070, which is ... Neat.
I haven't read Target: UCAS's Detroit or Boston (*spits*) chapter in a while, but I recall downtown is more controlled than usual because Ares' global HQ is there. However, there is still business to be done. As well, I understood the entire metroplex to be under Knight Errant. But if you have Target: UCAS you have 99% of the info on Detroit.
* I still can't read her many comments without thinking that this street witch/mage was accused of being Sheila Blatavska and thus Alachia by Elijah in
Loose Alliances (*spits*) because there is
no way in Hell Alachia is writing her posts.