[Mr. K]

" Could American negotiators have known that within a year gold would be discovered

You can bet on it...

[roadcat]

Could American negotiators have known that within a year gold would be discovered

Lots of speculation about that. John Sutter supposedly discovered gold with his employee James Marshall. However, he was no saint. Johann Sutter was a con artist, conning the governor into giving him a land grant. He wheeled and dealed, and probably knew of the gold and may have secretly told the Americans it existed. In any event, it got out of his control when the gold rush happened, and he died nearly broke.