Hmm. I hadn't thought of it that way. I just remember it being set in Mississippi. Though you're right; the governor in the movie was based on a governor of Texas.
It was Jimmie Davis who wrote You Are My Sunshine. Also you neglected to mention the Tennessee Valley Authority, which was also part of the plot.
I had forgotten about the connection to Tennessee Valley Authority. There were probably other places mentioned. The Oklahoma town was Tishamingo.
The song You Are My Sunshine was a very popular song, my mother sang it to me when I was young.