I was going through some of my old photos of Nevada City for a blog post on Surewhynotnow which is located on MT 287. From what I can tell MT 34 was renumbered to MT 287 sometime between 1986 and 1989. I know US 287 was extended north into Montana by 1965 which connects to MT 287 in Ennis. Interestingly it seems that MT 1 was renumbered as MT 287 sometime after 1958 (I'm seeing this all on historicaerial topo maps) and it stayed that way until US 287 entered the state. Does anyone have any insight on either the pre-US Route version of MT 287 or why MT 34 was renumbered? The case of MT 34 renumbering it to MT 287 seems extremely odd, I'd be curious find out why that happened.
http://surewhynotnow.blogspot.com/2018/08/ghost-town-tuesdays-nevada-city-montana.html
I don't really know why MT 34 was renumberd to 287. All I know is that most of MT 287 and 41 are part of the Vigilante Trail. Corco or Andy may know more about it.