On May 26, 1805, Lewis and Clark first sighted the Rocky Mountains. From the Journals of Lewis and Clark:
"May 26, 1805
[Lewis]
Sunday May 26th 1805.
Set out at an early hour and proceeded principally by the toe line, using the oars mearly to pass the river in order to take advantage of the shores. scarcely any bottoms to the river; the hills high and juting in on both sides, to the river in many places. the stone tumbleing from these clifts and brought down by the rivulets as mentioned yesterday became more troublesome today. the black rock has given place to a very soft sandstone which appears to be washed away fast by the river, above this and towards the summits of the hills a hard freestone of a brownish yellow colour shews itself in several stratas of unequal thicknesses frequently overlain or incrusted by a very thin strata of limestone which appears to be formed of concreted 〈cemented〉 shells. [1] Capt. Clark walked on shore this morning and ascended to the summit of the river hills he informed me on his return that he had seen mountains on both sides of the river runing nearly parrallel with it and at no great distance; also an irregular range of mountains on lard. about 50 mes. distant, the extremities of which boar W and N. W. from his station."