I've been on a research project off and on for almost two years trying to find a paper trail for certain people in and around M.C., prior to when the Yellowstone Journal began in July, 1879. Ironically, my target interests include about two years before that time and up to about July, 1879.
According to his bibliography Hoopes searched mostly the Montana papers, and the Bismarck Tribune. I have subsequently scoured all the same newpapers as did Hoopes.
But he also used many memoirs, diaries, old journals, unpublished manuscripts and old books etc. and I'd like to know where some of them reside.
I too would love to know where his notes are, because it has become apparent to me Hoopes tended to downplay things that might shed too much bad light on old Miles City - not that it isn't a forgone conclusion that Milestown was a rip-roaring boomcamp like the rest of them. My focus is on outlaws, lawmen, and the action that took place amongst them.
Is there any article in particular you are wondering about? I ran across some that Hoopes used when I was 'running' the microfilm in Butte, Helena and Miles City. Then later requisitioned the Bismarck paper and saw more.