I read this in my Motorhome online pub. (RV TRAVEL) this morning. Sounds Reasonable. What say you??

TRIVIA
Before the Civil War, many local banks issued their
own currency. In New Orleans, where there was a
large French speaking population, a bank produced a
$10 bill, with the term "Dix" printed on it, which means
"ten" in French. Soon, the bills became known as
"Dixes." Riverboat men from the north, when heading
south, would say they were going downriver to pick up
some Dixes in Dixie Land. In time, the term Dixie came
to be applied to all of the Deep South.
BEBOP