Environment changes man.
Here in the midcontinent, at the mid-century, the frontier and the ways of the frontier were writing their imprint on the human product of our land.
The first great caravans of the Platte Valley, when the wagon-trains went out hundreds strong, were not the same as the scattering cavalcade of the fur hunters, not the same as the ox-trains and mule-trains of the Santa Fe traffic.

The men who wore deepest the wheel marks of the Oregon Trail were neither trading nor trapping men, but homebuilding men--the first real emigrants to go West with the intent of making homes beyond the Rockies.
The Oregon Trail had been laid out by the explorers of the fur trade.
Zealous missionaries had made their way over the trail in the thirties.
The Argonauts of '49 passed over it and left it only after crossing the Rockies.

But, before gold in California was dreamed of, there had come back to the States reports of lands rich in resources other than gold, lying in the far Northwest, beyond the great mountain ranges and, before the Forty-Niners were heard of, farmers, homebuilders, emigrants, men with their families, men with their household goods, were steadily passing out for the far-off and unknown country of Oregon.
The Oregon Trail was the pathway for Fremont in 1842, perhaps the most overvalued explorer of all the West; albeit this comment may to some seem harsh.

Kit Carson and Bill Williams led Fremont across the Rockies almost by the hand.

Carson and Williams themselves had been taken across by the Indian tribes.