Where were the Clampetts from?

According to the book "The Beverly Hillbillies" by Stephen Cox:

When they were filming the pilot for the show, they built a shack to be Jed's mountain home...

"The patch of land they chose appeared as rustic and as rural as any place in the Missouri Ozarks."

The Clampetts were from the Mountains of Tennessee, the fictional name of the town was Bugtussle. On a couple of the episodes, they go back for a visit.

Here is a site that talks about the show, and it mentions where they are from:

http://www.timvp.com/beverlyh.html