By August 8, 1805, the two commanders had become concerned about their difficulty in contacting the Shoshone. Over 2,000 miles from home, with an unknown distance ahead of them, it was vital that they find horses. Sacagawea had confirmed that they had entered lands familiar to the Lemhi Shoshone, but there had been no direct contact.
Lewis wrote: "the Indian woman recognized the point of a high plain to our right which she informed us was not very distant from the summer retreat of her nation on a river beyond the mountains which runs to the west. This hill she says her nation calls the Beaver's Head, from a conceived resemblance of it's figure to the head of that animal...as it is now all important with us to meet with those people as soon as possible I determined to proceed tomorrow with a small party...and pass the mountains to the Columbia; and down that river untill I found the Indians...without horses we shall be obliged to leave a great part of our stores..."
On August 9 Lewis and three men moved off to scout the Lemhi Pass. The trip would take him across the Great Divide on a mountain summit at the edge of the Louisiana Purchase. With this view across the mountains ahead, he could see the death of a dream.
The "River of the West," the "Northwest Passage," the river of commerce through flat, open land that would connect two oceans, the route they had been sent to find, did not exist. His journal entry of August 10 held out some hope, but he did express misgivings:
"I do not beleive that the world can furnish an example of a river runing to the extent which the Missouri and Jefferson's rivers do through such a mountainous country and at the same time so navigable as they are."
No apparent course to the ocean was visible or known to them. Again, the expedition would have to depend on help from the tribes to find its way west.