How Dixie Got Her Name 

The Old Citizens Bank of New Orleans stood for many years on Toulouse Street between Royal and Chartres. In the financially troublous times of the late 1830s, when panic was in evidence everywhere and "wild-cat banks" played havoc with the prosperity of the country, the Citizens Bank won fame for the stability of its notes and bills that readily passed current everywhere. Its ten-dollar note bore upon its back the French word for ten - Dix. Hence, these banknotes throughout the West were familiarly referred to as Dixies. The transition to Dixie, as applied to the land from which these notes came, was naturally made. The South has been "Dixie" ever since.

~~  From the History of Louisiana by Chambers
Vol. I, pg. 584