MLS Commissioner Don Garber explains his reasoning as to why Atlanta was chosen as the city to receive an MLS team. Stating that Atlanta is very different than the other US or Canadian cities and extremely diverse, but that the large Hispanic population in the city had a lot to do with it the decision as well as that the city is very young. It was a probable choice when the league first started but finally got its team due to a new 1.2 billion downtown stadium. In addition, Georgia is a top ten state for youth soccer. Read more here.
http://www.mlssoccer.com/news/article/2014/04/16/mls-commissioner-don-garber-and-new-owner-arthur-blank-explain-why-pro-socce