A bit of a different ATL from the ones usually featured here.
Basically the USA (and UK) are quite anomalous among Western nations for having a largely middle-income suburbia and a largely lower-income inner city (with small pockets of upper-income areas, think Upper East Side in Manhattan).
Although since the 1980's this pattern has changed with gentrification, it still applies to the USA far more in relative terms than Continental Europe and Australia, where a pattern of suburban poverty and urban affluence tends to apply.
With a POD no later than the end of WW2, what would be necessary to have the inner-city of American cities been seen as the desirable place to live? For instance have Harlem, Lower East Side and the South Bronx maintained rather than neglected so no urban decay and have these areas seen as desirable middle-class locations to live. Have places such as the North Bronx and further out seen as undesirable places to far from cultural attractions, city life, etc to be inhabitied by anyone other the poor and minorities with no other choice (due to discrimination etc). Just used NYC locations for simplicity. Perhaps in ATL by 2007 people complain of suburban decay and suburban blight?
Bonus points if you get the POD no later than the end of WW1 (which being prior to the widespread use of the car may be a more plausible POD).