TL;DR -- Paintings by Remington and Jackson give a good flavor of the times.
There were several ways to start this post, however using Remington is very much apropos. Picked this photo up from the page about Jedediah Strong Smith on the Legends of America site. We got to Jedediah through articles by Judge Thompson in Dr. Frank's The Massachusetts Magazine where the Judge wrote of his journey out west (over land, to the left coast, and back) in the early days. However, he was in a later time that that of the mountain men who were associated with the fur trade.