GUEST: This is a map of California. My great-grandfather, who was a farmer in Ohio, decided that he would come out here and look for gold.

APPRAISER: To become a 49er, basically.

GUEST: That's right.

APPRAISER: Most of the maps that were created in those first years were promotional, produced sometimes in the East Coast, but sometimes here. But they didn't have a great deal of knowledge about the actual parameters of what became the state of California. This map was produced by Britton & Rey, who were two very early lithographers in the city of San Francisco. And this map is one of their earliest renditions of the state. It was highly prized because it provided one of the first and most accurate maps of the border region here with what they call Utah at the time before it was Nevada. Not all the details are accurate, of course. What is now Lake Tahoe they call Pyramid Lake and it seems like it's a little farther north than where it normally would be. Now, because this map was created practically for miners in San Francisco, very, very few of them survived. They were taken up in this small pocket into the Sierra and there would be issues like you have already here, with some tearing and ripping. When it's folded up, of course, the paper starts to fray and break along these lines. As a result, very, very few of these maps have survived. In fact, no examples of this map have come for sale in over 30 years at auction.

GUEST: I see.

APPRAISER: And only a handful exist in institutions. I would say that a map of this stature would probably have an auction value of $10,000 to $15,000 and could well sell for a great deal more.