On February 19, 1806, President Jefferson addressed a joint session of the Senate and House of Representatives, and announced he would present to them a letter from Lewis, a "statistical view...of the Indian nations inhabiting the territory of Louisiana, and "a general map of the country between the Mississippi and Pacific, from the 34th to the 54th degrees of Latitude," based on Indians' information.1
Clark evidently began compiling this map after meeting with Hugh Heney at Fort Mandan on December 18, 1804, and continued adding information acquired from other traders, as well as from Indians. He sent it back east on the keelboat in April of 1805. Nicholas King made two copies of it, but neither was ever engraved, so the members of Congress never saw it.2
At this point, Clark placed the mouth of the Yellowstone at 107° west longitude, or a little more than 200 miles west of its actual location at 104° west. Lewis arrived there on April 25, 1805, having pushed on overland in advance of the main party, hoping to make the necessary celestial observations without delaying the company's progress. Unfortunately, clouds obscured the moon, so that half of the exercise had to be abandoned. On his return in August of 1806, he was in a hurry to catch up with the main party, and stopped there only long enough to read the note Clark had left him.
"The King," "The Heart," "Battle Hills" and "The [Bears] Tooth," were landmarks along the Old North Trail, which Indians had identified for earlier travelers. They were about the only topographic features in this part of the continent shown on Nicholas King's map of 1803, and evidently they were still significant to the Indians who tutored Clark at Fort Mandan. They are all absent from Clark's 1814 map.
King's map had placed the northern and southern sources of the Missouri River between 46° and 50° north latitude. Clark has concluded from traders' and Indians' accounts that the Yellowstone begins well below the thirty-ninth parallel. Actually, its southernmost source is at about 44° north latitude.
The "war path of the Big Bellies Nation" here crosses the Yellowstone near the Oak-tar-pon-er (now O'Fallon's Creek); in the map Clark drew from Sheheke's information.
To see how Clark's understanding of the geography of the Northwest evolved, compare this with King's map of 1803 and Clark's map of 1814.
1. Donald Jackson, ed., Letters of the Lewis and clark Expedition, With Related Documents, 1783–1854 (2nd ed., Urbana: University of Illinois Press, 1978), 1:299.
2. Moulton, Journals, Vol. 1, Atlas, 8-9. The detail shown here is from Atlas map 32a, the so-called "State Department copy." See John Logan Allen, Lewis and Clark and the Image of the American Northwest (New York: Dover, 1975), 97–104. Two of King's copies of Clark's 1805 Fort Mandan map are now extant; see Moulton, op. cit., 32a and 32b.