GUEST: Well, the letter's been in the family probably since 1849, Chris. It was passed on to me. I was interested in it, had it preserved by one of the local archivists.

APPRAISER: The date of 1849, of course, is crucial. I mean, that was the year something was found in the West.

GUEST: Gold, yes.

APPRAISER: Gold. And this was an event that electrified the nation, and people from all over the eastern part of the country emigrated to the west. It's signed at the end by M.O. Whelpher, and up at the top it's dated Fort Childs, May 16th, 1849. It says, "We started from Saint Joseph. "We are now 250 miles from that place, "on the Platte River, in the country of the Pawnees, "a powerful tribe. They are, at present, at war with the Cheyennes." Further down, he talks about the number of people who were making this journey, too. "We have passed 114 wagons with ox teams and 50 mule teams, and a multitude innumerable behind us." And here you get that sense of a big exodus. "We saw the grave of one man, and three men have died behind us." "We go from 14 to 22 miles per day. It is 350 miles to Fort Laramie." That's Wyoming territory.

GUEST: Yes, it is.

APPRAISER: One of their way stations. And then he says, "If you don't hear from me for a while, "don't be concerned. You must remember that I am in the land of uncertainty." I love that phrase. He was. This was a major exploration for him. "When you write, write two letters, one to Sutter's Fort, the other to San Francisco." So it's clear from the letter where he was going and what was motivating him to make this arduous and very difficult journey. And I have to say, as a manuscript specialist, that this is the only letter I've ever encountered in 20 years, written by a participant on an actual wagon train.

GUEST: Really?

APPRAISER: You do see letters written after the fact or before departure and diaries kept during the journey, but this is the only actual letter I've seen written by a participant. What can an owner do with such a letter? Well, you've done one very smart thing already. You've had some very discreet conservation to protect it from damage and weakness at the folds. You've got it flattened rather than folded up in a small parcel, and as a rarity, written on the actual wagon train heading west across the prairies, I would put a value somewhere in the range of $3,000 to $5,000.

GUEST: Oh, my God.

APPRAISER: Seems like a lot for a letter of someone who's not a historical figure.

GUEST: Yeah, yeah.

APPRAISER: But the content here is really key.