Everything I've ever read on Atlanta (and really, most large, suburban American cities that developed after the advent of the car) leads me to believe that there were many, many terrible decisions made in the decades after WW2 that resulted in them being massive, spread out, balkanized cities that are far too dependent on cars and freeways and have little or no centralized decision making on transit or other infrastructure. It's mind boggling to me that the city of Atlanta is actually only something like 10% of what the Atlanta metro area, population wise.