As a route of western expansion the Missouri River has few equals.  Lewis and Clark spent three weeks, from May 24 through June 13, 1805, exploring the segment that is now the Upper Missouri National Wild & Scenic River.  Today this portion is considered to be the premier component of the Lewis and Clark National Historic Trail. 

Lewis writes, May 25, 1805:

"the air of this quarter is pure and helthy.  the water of the Missouri will tasted not quite so muddy as it is below"

May 31, 1805

" as we passed on it seemed as if those seens of visionary inchantment would never have an end; for here it is too that nature presents to the view of the traveler vast ranges of walls of tolerable workmanship, so perfect indeed are those walls that I should have thought that nature had attempted here to rival the human art of masonry had I not recollected that she had first began her work".