SOUTH was originally written and recorded as a jazz instrumental tune, that is, without lyrics. It was written by Bennie Moten and Thamon Hayes, and recorded by Bennie Moten's Kansas City Orchestra in 1924. The same orchestra made another recording in 1928. You can hear both of them at The Red Hot Jazz Archive. You can hear another instrumental version from 1944 by Kid Ory's Creole Orchestra

Lyrics were written later. Here is the catalog data from Indiana State University:

Title: SOUTH.
First Line: Down below that old Dixon Line, there's a place that really is fine
Chorus: Where the folks are happy and gay, and the easy way is the right way
Music by: Moten, Bennie, and T. Hayes.
Words by: Charles, Ray.
P/P/D: New York : Peer International Corporation, c1941.
Location: SPC, KIRK PS 1940-1941

Allmusic.com has sound samples of recordings of vocal versions by The Maddox Brothers and Rose, Lynette Morgan and the Blackwater Valley Boys, and Bob Scobey's Frisco Band. I have listened to them and pieced together the following lyrics. I don't know if they're complete. I have shown variants in parentheses:

***

Down below that old Dixon line,
There's a place that really is fine.
Don't you know what I'm talkin' about?
You want to find out, then take a trip with me (or "to meet me")
Down below that old Dixon line.
Where the sun is (or "stars are") happy to shine.
Where a friendly face is common to see.
That's where I'm longin' to be.

Where the folks are happy and gay,
And the easy way is the right way,
Where the bees make honey (or "music") all day.
Don't you know you're right next to heaven down south
Where the moon shines mellow and bright
And the breeze plays tag with the night.
That's where the sundown gals hold you tight.
Lordy, how I love the south!