One piece I'm working on right now has to do with the Salmon River, and specifically the Middle Fork of the Salmon River. In my research, I came across the book River of No Return by Robert Bailey, originally published in 1935 and then republished in 1947, which is the edition I checked out from the library today.
I found one thing I was looking for—references to what I think is the first successful boating expedition down the Middle Fork of the Salmon River in a rubber raft. I also found a nightmarish index that is unnecessarily sectioned into things like "Places" and "Rapids" and "Boats." It may as well have been sectioned into the definition of nouns: people, place, thing—and in fact, that's not far off from what it is; one of the more frustrating index sections is titled "Miscellaneous."
But the part that got my attention was the unnecessary bifurcation at the beginning of the index: Page 733 is where the index begins, and the section that starts there is labeled "Individuals." What it means, with few exceptions, is "white people," because on page 744, the next section of the index is titled "Indians."