On this day in Lewis & Clark history...
Clark, J. Fields, Potts, and York set out ahead of the boats in order to find the Shoshone. They find an Indian trail and see several Bighorn sheep. Lewis brings the canoes 21 miles up the Missouri River to Eagle rock at modern Holter Lake.
From the journals...
July 18th Tursday 1805
a fine morning passed a Considerable river which falls in on the Stard Side and nearly as wide as the Missouri
Thursday July 18th 1805.
this handsome bold and clear stream we named in honour of the Secretary of war calling it Dearborn's river.—
Dearborn and Missouri rivers

Thursday July 18th 1805.
I have observed for several days a species of flax growing in the river bottoms the leaf stem and pericarp of which resembles the common flax cultivated in the U' States....the seed are not yet ripe but I hope to have an opportunity of collecting some of them after they are so —— if it should on experiment prove to yeald good flax and at the same time admit of being cut without injuring the perennial root it will be a most valuable plant
Blue flax, Linum perenne var. lewisii
