Coming of Age in Mississippi

So I am reading a book called "Coming of Age in Mississippi" by Anne Moody, which is set in post-antebellum Mississippi. She had become Homecoming Queen and during the parade through her town, everyone began to sing Swanee River.

"The faces of the whites had written on them some yearning. The Negroes looked sad...There was something about "Swanee River" that touched most of those old whites singing along with the band. There was also something that made the old Negroes even sadder. I got a feeling that there existed some kind of sympathetic relationship between the older Negroes and whites..."

This passage stuck out to me because it made me think about our previous class discussion about the lyrics of this song. From my knowledge this book is at least semi-autobiographical , which suggests that people viewed this song as nostalgia. when Moody states that it symbolizes a relationship between whites and blacks it suggests that the song evokes dependence that each of them had on one another.
One of the ironic things to me was that I do remember that the composer of the song had not grown up in the south yet the song reminds southerners of the old days.