The Mississippi River Delta along Hwy 61 is pretty flat, but there is a lot of history. Clarksdale, MS has a rich tradition of Blues Music, Black American Cultural history and many small museums along the way.
South of Clarksdale you can pick up Hwy 1 along the river. You will have to seek some small roads to get over to Hwy 1. Take your time, BBQ, Blues and The Delta will infuse your soul.
When you get to Hwy 20, veer a bit east and travel some of the Nachez Trace. Beautiful, scenic, lonely. Stop at The Nachez Trace Museum in Clinton. A pretty little stop.
South of Nachez in St.Francisville, LA check out Magnolia Cafe for lunch or seek a haunted plantation. If you use Google and ask locals, you will have an adventure!