For me this is guess work as I don't know the URLs, but is it possible that people in Nashvile use other search terms than you are ranking for or have other ways to search for property? ans do you use those search terms as well? I've seen somthing simular within Germany where it turned out people were using a slightly different version of the keywords.
Are all pages in the Nashville section being measured properly? Is the GA code implemented on all the pages? As you mention that you have only 70% of traffic compared to that of Atlanta.
And I think it could also be a matter of trust. is your brand new in the Nashville area? Than people might be more responsive towards your competitors.
Geddy