There are several rumors (or shall we say "tall-tales"?) of how #60 ended up in Idaho Springs.
One of these is that the engine was bound for display in Silver Plume, was run up the canyon under her own power, but suffered some mechanical failure in Idaho Springs, which is why it ended up on display in that town.
Not that I believe this or any of the others entirely. To be honest I don't know in full exactly how the engine was transported to Idaho Springs, whether by truck, dead in train, or under its own steam. I kinda doubt the latter though.
My 2 cents.
~Shane