I suspect that this image appears to have been cut from the United States Pacific Rail Road Expedition and Survey books, dating from the mid 1850s.

It is mounted on a hard board; the others that I bought this one with had a sticker from "C.W. Unger Rare Books, Pottsville, PA" on the reverse, which I believe is the individual who cut this image from its original book.  Also on the reverse is a handwritten caption, that appears to be "Valley of Bill William's Fork Vol. 2 page 102".  

Board measures 14 x 12 inches; image measures 8.75 by 5.75 inches.