The National Public Radio site has an article on the song which opens with these words about the song Dixie (emphasis added):
Nov. 11, 2002 -- "Dixie" -- a song strongly identified with the South -- stirs emotion and exposes timeworn rifts across American society.
It has been that way almost since "Dixie" was born in the days just before the Civil War. Adopted as a Confederate anthem, it was offered up by President Abraham Lincoln as a gesture of reconciliation after the war. It's accepted with affection by many whites and scorned by many blacks. ...
Wikipedia has an informative entry on "Dixie." Here is a quote (emphasis added):
The song became the unofficial anthem of the Confederate States of America during the American Civil War. This and the tune's minstrel-show origins have created a strong association of "Dixie" with the Old South. As a result, some today view the song as offensive and racist while others see it as a legitimate part of Southern heritage.