As a way back when coin and currency dealer [not any more, but it paid for my first year of college] the "Dix note" long preceded the song. I believe it actually had the word "Dix" under a large Roman numeral "X." The story I heard was that Dixie was anywhere the notes circulated. These notes were from the era of local and private banks and, from my recall, were exceptional in that they were generally honored and not defaulted. The circulation of these fly by night banks led to the establishment of a national currency and to Jackson's effort to create a cenrtalized federal banking system.