Ya spose that's some of them damned Yankees still hidin out from the Civil War???
That would be the Alabama "black belt" which, ironically, was where George Wallace got his start in Alabama politics.
That East-West line in Alabama is known as the Black Belt, so named because of the rich black soil for our farms, and coincidentally, home to the highest proportion of Black to White farmers this side of Zimbabwe. Oh, and we've also got an Indian reservation in Alabama (no gambling of any note, though).
That map is inaccurate, though. At least two of those counties should be white, not red or blue.
The Alabamians who sided with the Union in the Civil War, however, were on our Northern border. They formally seceded from Alabama, but unlike the illegal state of West Virginia, didn't receive permission to have their own state from Congress (hence, denying the South 2 additional senators).
Such is life.
I don't know SW. It looks like its runnin' east to west to me. ;-)