Clark's Map of the Falls

Clark's map, engraved for the first edition of the journals
Pass the cursor over the image to read full details.

Clark's Map of the falls of the Missouri
From Paul Allen, ed.,History of the expedition under the command of Captains Lewis and Clark, to the sources of the Missouri, thence across the Rocky Mountains and down the river Columbia to the Pacific Ocean. Performed during the years 1804-5-6. By order of the government of the United States. (2 vols., Philadelphia: Bradford and Inskeep, 1814), Plate 3.

The copy from which this image is reproduced was owned by Henry Villard (1835-1900). Villard was the principal financier of the Northern Pacific Railroad, completed in 1882, which paralleled much of Clark's route through the Gallatin and Yellowstone valleys.


Finding "the Fall"

During the winter of 1803-1804 the captains gained much valuable information and advice from a Scotsman in St. Louis named James Mackay. In 1795 Mackay, the manager of the Spanish-controlled Missouri Fur Company's operations on the lower Missouri River, sent John Thomas Evans on a mission to find the elusive Northwest Passage. Evans got no farther than the Knife River villages, but while there he acquired information from the Mandans and Hidatsas about the land that lay between their homeland and the Rocky Mountains.

The Indians, Evans reported, "have but a Confused Idea of the upper parts of the Missouri."

Nevertheless after all the Information I could collect, it appears that the Missouri takes it source in abt. The 40th deg. North latitude from Whence it Runs to the North (between the chains of the Rocky Mountains) as far as the 49th deg. Latitude that thence running East it falls over the East chain of the Mountains in the great plains across which it runs to the East till it reaches the Maindaines . . . There is no other fall, in the whole Course of the Missouri, but where it falls over the Rocky Mountains, in the plains, as I have said before. This fall it is Said, is of an astonishing height, from the Situation of the Country and the Meanders of the River I suppose this fall to be 200 leagues West of the Mandaines.1
link to detail of Evans's mapNo doubt Evans' impression of Indian "confusion" was a result of communication problems across the language barriers between two cultures accustomed to different ways of measuring time, distance and direction; having different reasons for traveling through the same land; and using different modes of travel.2 In view of that, it is no wonder that his conclusions spanned a wide spectrum of truth and probability. For example, the fortieth parallel runs near Provo, Utah, and Denver, Colorado, more than 300 statute miles south of the farthest source of the Missouri, which is a lake at 44° 33' North Latitude.3

On the other hand, the river twice touches its northernmost point at about the forty-eighth parallel – downstream from Fort Benton, and again at Brockton in extreme northeastern Montana – which is only sixty-nine statute miles south of Evan's forty-ninth. But his understanding that the landmark waterfall was downstream from the river's northernmost point would lead to erroneous expectations, with commensurate frustrations to the traveler.

Evans was able to ask questions, to translate the Indians' answers, and factor in his own experience, in ways that would enable him to estimate the distance from the Knife River villages to the falls with reasonable accuracy. Although the league is historically a variable unit of measurement, in Clark's day it was equal to three statute miles.4 Therefore, by Evans' estimate the waterfall would be 600 river miles west of the Mandan villages. It is actually 733 river miles away today, and given its geological constraints within that part of the Missouri River, the distance could not have been much different in 1805. One can imagine the apprehensions in the captains' minds as the miles added up. Without yet having come upon the falls, the Corps faced a crucial decision at Maria's River – at mile 876 according to Clark's "courses and distances." When they reached rapids (now known as the Big Eddy), six river miles below the falls, Clark's estimates added up to 930.5 miles.

In their deliberations at the mouth of the Marias over which branch to ascend, Lewis recalled (9 June 1805) that the Indians at Fort Mandan had informed them that "the falls lay a little to the South of sunset from them," and that "the falls are below the rocky mountains and near the Nothern termineation of one range of those mountains." His own observations seemed to corroborate the Indian information: A range of mountains, "which appear to terminate S. W. from this place and on this side of the unbroken chain of the Rocky Mountains gives us hope that this part of their information is also correct." (He could have been seeing the overlapping island ranges now called the Highwood, Big Belt, and Little Belt mountains.) Then he added, with an uncharacteristic hint of pessimism – or perhaps just cynicism over the efficiency of cross-cultural communication – "there is sufficient distance between this [place?] and the mountains for many and I fear for us much too many falls." A mere five days later he would discover the true irony of his remark.5

One other communication barrier was simply a grammatical bump, though we can well imagine Lewis's mixed feelings when he discovered the truth. Evans understood that the waterfall was singular, while his informants knew it was plural. Whether the error lay in the telling or the hearing is impossible to say.

Taking Inventory

During his extended exploration of the falls on June 14, Lewis discovered that a portage around the falls on the north side of the Missouri, which Indians back at Fort Mandan had recommended, "will be attended by much difficulty in consequence of several deep ravines which intersect the plains nearly at right angles with the river to a considerable distance, while the south side appears to be a delightfull smoth unbroken plain; the bearings of the river also make it pobable that the portage will be shorter on that side than on this."

When Clark caught up with him on the sixteenth, the two of them discussed the situation. Early in the morning of June 17, 1805, while Lewis supervised preparations for the portage, made some celestial observations, and monitored Sacagawea's slow recovery from a serious illness, Clark set out to look for a likely portage route on the south side of the river. Taking five men to help him, he made a detailed inventory of the falls and rapids that Lewis had observed on the thirteenth and fourteenth. The summary of his discoveries is represented by the sketch map he drew of the falls, and its refinement in the engraving that accompanied the first edition of the Journals.

Modern US Geological Service map of the Falls of the Missouri River

"Shineing Mountains"

One of the most encouraging sights in the neighborhood was the snow on the surrounding mountains, which jibed with another feature of Evans's map. On 20 June 1805, Clark observed:

Mountains to the South & S. E. of us Sometimes Snow. at present there is no Snow on those mountains; that which covered them a fiew days ago has all disappeared. the Mountains to the N. W. and West of us are Still entirely Covered are white and glitter with the reflection of the Sun. . . . I have thought it probable that these mountains might have derived their appellatin of Shineing Mountains, from their glittering appearance when the Sun Shines in certain directions on the Snow which Cover them.


1. A. P. Nasatir, ed., Before Lewis and Clark: Documents Illustrating the History of the Missouri 1785 -1804 (2 vols., Lincoln: University of Nebraska Press, 1990), 2:498.

2. See James P. Ronda, "'A Chart in his Way': Indian Cartography and the Lewis and Clark Expedition."Great Plains Quarterly, 4 (Winter 1984), 43-53.

3. Lewis ultimately left "Jefferson's" river – today's Beaverhead River – today's at the forty-fifth parallel and turned westward. He did not know he was still 128 river miles from the Missouri's ultimate source. Nor did he have any reason to care, since he knew from Sacagawea's assurances, as well as from the heavily traveled Indian road leading up today's Horse Prairie Creek, that he was as close to the waters of the Columbia River as the Missouri would lead him.

4. Noah Webster, A Compendious Dictionary of the English Language (1806; reprint, New York: Crown Publishers, 1970).

5. A measure of Lewis's state of mind during this period of the journey is suggested by the comment he recorded more than six weeks later, on 24 June 1805: "I fear every day that we shall meet with some considerable falls or obstruction in the river notwithstanding the information of the Indian woman to the contrary."