From an 1859 song, it's a nickname for the Old South
In the decades after the Civil War, Dixie 
regained some of it's former nationwide popularity  at least... [DOC] [TLE] [Appreciation] | The 23 Best Train Songs Ever WrittenMaybe, by ... [PAR] Jun 26, 2014 ... Ascending the Alleghanies, Harper's Magazine (June 1859) ...