The only section with significant hills is Cedartown to Rockmart -- and there are some short but sharp grades -- be careful going downhill.
My favorite section is from the GA/AL line west to Piedmont, AL. The old railroad right-of-way cuts through the Appalachian mountains so it's very pretty.
If you're doing this in hot weather, think about the distance between water stops. One section that I can think of that's pretty long is Cedartown to Piedmont: about 23 or 24 miles.
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Sheriff: You have a lot of experience with bounty hunters, do you?
Mattie Ross: That is a silly question. I am here to settle my father’s affairs.
Sheriff: All alone?
Mattie Ross: I am the person for it. Mama was never any good at sums and she could hardly spell “CAT”.
--from the movie True Grit (2010)