How to date this?

Hi all. I picked this sign up at an estate sale. It is hand painted and measures 11x20. This is heavy metal not tin. There aren't any markings on it. The history of the area where the estate sale was, is near the Conasauga river running through what was Cherokee Nation and old federal rd(trail of tears). Does anyone have any idea how to tell age of the sign? Any wisdom is much appreciated.