"down into Louisiana" The map you linked to shows the Yazoo-Mississippi Delta aka "Mississippi Delta" ("the distinctive northwest section of Mississippi between the Mississippi and Yazoo Rivers") as ending about 25 miles from Memphis (and not including e.g. Plum Point, Mississippi, where Memphis bluesman Jim Jackson was reportedly born, or Hernando, Mississippi, where Memphis bluesman Robert Wilkins was born) and being immediately on the other side of the Mississippi River from part of Arkansas and part of Louisiana (ending about 200 miles from New Orleans).