Yeah, see my comments above.
Also, look at the annexation map for Detroit:
http://detroit1701.org/Annexation%20Map.html
Notice anything? If you compare it to the WSJ density map, the most hollowed out areas roughly correspond to the sections of the city annexed before 1910. These were neighborhoods that needed to be constructed around transit lines, since the personal automobiles were not widely owned. Remove the transit system and the neighborhoods evaporate. Seems like every other very large city besides Detroit realized this fast enough to save themselves before it was too late.