I just got a PM asking about how I got these leads, thought I would post my reply here for all to see- pretty good info for research ideas-
Well, the bulk of them I got lucky on- heres the story....
Back in the 60's a hippy couple traveled all around the state of Oregon checking out all the neat sites they could lay their hands on. Along the way, they did research and made careful notes. These notes and specific sites, they eventually turned into a map and tried to market it. They made 1000 copies and sold them at flea markets, etc. Most wound up in the trash eventually. I found an old copy in pretty good shape, but it was stained and faded. I finally got a hold of the guy who purchased the rights to the map, planning to make copies and market them which he never got around to, and as luck would have it, he had about 10 of the originals left in his garage, all brand new!
I have traveled to enough of these sites to know that the info is very accurate as far as location goes. Dead on. I've driven right to indian caves that you will not read about anywhere!
Most other leads I get from a local bookstore that buys and resells books from the public. I look for older books pertaining to my area. You would not believe the amount of information that gets left out of new maps and books! I think most of it comes from the idea of preserving these old sites, they don't want the general public to know about. When it comes to books and maps, the older, the better!