One of the wonderful things about the Lewis and Clark Expedition, of course, is the image of America as the Garden of Eden that their journals present. I think one of the ones that's resonated a lot for people over the years, reading their journals, is the image of a kind of American Serengeti, from North Dakota across the Montana plains to the Rocky Mountains.
No American Serengeti, of course, is complete without vast herds of buffalo, and you have descriptions of those kinds of herds throughout the Lewis and Clark journals, from the time they reached the borders of Montana right on through the Three Forks and beyond, basically to the Continental Divide.
And then, one of the things lots of people noticed over the years is that if you follow Lewis and Clark across the Continental Divide, down into the Bitterroot Valley, then over the Lolo Trail into Idaho, progressively, the images that you get are of fewer animals. In fact, the accounts of Lewis and Clark crossing the Lolo Trail, of course, is an account of people who are basically having to eat their own horses. Once they arrive among the Nez Perce they're purchasing dogs in order to eat. And one of the interesting new developments in Western environmental history that sort of reflects on the differences between what Lewis and Clark saw east of the divide, and what they saw west of the divide, has to do with an argument that centers around something called Indian buffer zones.
If you remember from reading the Lewis and Clark journals you know that after they leave the Mandan Villages...after the winter of eighteen-four/eighteen-five...they journey for more than a thousand miles up the Missouri River, and never see an Indian. They don't see Indians again until they cross over the Continental Divide and encounter Sacagawea's band of Lemhi Shoshonis.
So, one of the arguments that scholars are making for the tremendous abundance of animals east of the Divide,as opposed to the relative paucity of animals west of the Divide, is that those two situations reflect as much as anything else the different diplomatic situation of Indians on the two sides of the Divide. East of the Continental Divide, the Blackfeet for several generations had done everything they could to keep other tribes out of the great bison region along the upper Missouri River. The difference in animal populations, in any case, east and west of the Divide, a lot of people are arguing now, has a good deal to do with the idea of buffer zones.
The distinction is this: The tribes west of the Divide were mostly at peace with one another--when you consider the Bitterroot Salish, the Nez Perce, the Cayuse, and the tribes along the Columbia River--those people were able to move freely through the mountain country and the plateau country to the west of the mountains without fear of getting involved in skirmishes with one another. As a result of the relative peace west of the Divide, then, animal populations could be hunted throughout that region, and were, to the point that Lewis and Clark encountered relatively few animals.
East of the Divide, however, what scholars call buffer zones existed in several places along the Great Plains, and one of the areas where there was a major buffer zone in the 19th century--especially the early part of the 19th century--was along the upper Missouri. In that region, the Crows,the Arapahoes, the Mandan-Hidatasas, and the Blackfeet, all competed for buffalo. And in those regions where tribes competed for buffalo,you found, usually, no people living permanently--groups living out on the far periphery of those areas, and only making forays--hunting forays--into the interior, and often those forays ended up producing skirmishes with other tribes.
So the evidence is that the reason Lewis and Clark didn't see anybody from the Mandan Villages to the Continental Divide had a great deal to do with the fact that this was a contested region.
In fact, on the way back down the Missouri River in 1806, William Clark noted in his journal that, after traveling all the way to the Pacific Coast and back, they had encountered larger wildlife populations, as he put it,in regions that are contested by the tribes, than anywhere else. So that's an explanation for why so many animals in Montana and on the upper Missouri. That sort of Garden of Eden look probably didn't prevail everywhere across the Plains, but Lewis and Clark happened to travel right through the middle of one of the regions that presented this image of America as the Garden that we've all absorbed and loved, ever since.