IIRC some of the original FM allocations (1950's) were based on the last Census they had 1950!. This is the Federal Government after all.
From Wikipedia:
"1950 - 331,314 (metro 997,666)
1952 saw annexation of Buckhead, Adam's Park, Cascade & Lakewood adding 100,000 people (130 square miles)"
About civil rights: It is well known that the relative peace that Atlanta enjoyed was due to the business leaders - both black and white - who came together and decided that such conflict was "not good for business". As a result, the slogan "Atlanta: the city too busy to hate" was born. It had a positive impact nationwide.
(Also, many cilvil rights organizations were/are headquartered in Atlanta, and no good army fights its battles in its own headquarters!)