The Meandering Mouth of the Kansas

Page 6 of 6

Detail from Nicholas King's 1803 Map

King 1802 Map

Library of Congress, Geography and Map Division

Early in 1803 Albert Gallatin and Thomas Jefferson commissioned the Philadelphia cartographer Nicholas King to create a new chart for Lewis's use as a base map. The result was a compilation of details from at least seven or eight other 18th-century maps containing what was then believed to be the best geographical information about North America west of the Mississippi and between 30° and 55° north latitude. King's most recent source was the 1802 map by the British cartographer Aaron Arrowsmith, who relied partly on the explorations of Peter Fidler. On the King map the mouth of Kansas River can be interpreted to be at 38°18' N, 94°55' W; this places it 58 miles south-southwest (azimuth 197°) from its actual location (39°06'54" N, 94°36'36" W). The King map also shows the Missouri to make a sharp bend to the northwest at the mouth of the Kansas, and this northwest course continues to the Mandan villages. Both the size of the Kansas River and the change in direction of the Missouri's course influenced the captains to take the necessary astronomical observations at this junction.

Clark's Small-Scale Maps

Clark prepared four maps that depicted the junction of the Missouri and Kansas rivers; these maps bear the dates 1805, 1806, 1810 and 1814 (Moulton, Atlas, maps 32a, 123, 125 and 126). Clark prepared the 1805 map while at Fort Mandan, drawing this map at a scale of 1 inch = 50 miles (1:3,168,000). His method of preparing this map not known. Certainly he did not replot the Expedition's courses and distances taken while ascending the river (compare, for example, the area near the Big Bend of the Missouri in present-day South Dakota shown on Moulton's Atlas, map 32a with that on Atlas map 22).

In comparing the coordinates shown on the five maps shown here, it may be helpful to remember that 1° of latitude always = 68.9 statute miles; at 38° N, 1° of longitude = 54.5 statute miles; at 39°N, 1° of longitude = 53.8 statute miles.

Detail From Clark's 1805 Map

Clark's 1805 Map

Library of Congress, Geography and Map Division

When the expedition's courses and distances are plotted and matched to the expedition's coordinates for Camp Dubois and to David Thompson's coordinates for the Mandan villages (with adjustments for the latitudes the Expedition obtained along the way), the fit is much better than that shown on Clark's 1805 map. In fact, the match between the Missouri River's course produced from the Expedition's river survey and that shown on modern maps is far better than any single map published until the map by the Missouri River Commission in 1893. Unfortunately, the 1805 map was not matched to known coordinates and, on that map, the mouth of the Kansas River is shown to be 86 miles East-by-North (azimuth 86°) from its actual location.


Detail from Clark's 1806 Map

Clark's 1806 Map

Boston's Athenaeum

Clark's map of 1806 probably also had an original scale of about 1 inch = 50 miles. That part of the map downstream from Fort Mandan appears to have been crudely traced or redrafted from a copy of the 1805 map. There are, however, major differences in longitude of many junctions, and the latitudes of other river junctions downstream from Fort Mandan often differ by 5 to 10 minutes (6 to 12 miles). The mouth of the Kansas is 71 miles East-by-North of its true location.


Detail From Clark's 1810 Map

Clark's 1810 Map

Beinecke Rare Book and Manuscript Library, Yale University

The 1810 map also was prepared at a scale of 1 inch = 50 miles, and although the 1806 map likely was used as a base, the 1810 map appears to have been completely redrafted. There is considerably more detail (much of it merely ornamentation) on many of the streams and, once again, latitudes and longitudes of many important points, such as the mouth of the Kansas River, have shifted. Here it appears 15 miles East of its true location.


Detail From Clark's 1814 Map

Clark's 1814 Map

Library of Congress, Geography and Map Division

The 1814 map was prepared by Samuel Lewis from a map by William Clark. The map was published at a scale of about 1:4,300,000 to 1:4,500,000 (about 1 inch = 1° of latitude). The map bears a strong resemblance to Clark's 1810 map, but again, latitudes and longitudes of many important places differ from the predeceding maps. Now the mouth of the Kansas is 21 miles northeast of its true location. The 1810 chart, it should be noted, was Clark's master from which Samuel (no relation to Meriwether) Lewis made the drawing that the engraver used for the 1814 printing. The difference in the location of the Kansas was the result of an error in copying, and was not based on interpretaion of any navigational data.


What does this array of charts add up to? As has been shown (see "Comparisons and Conclusions"), Lewis's best observations, correctly recalculated, showed the Kansas joining the Missouri at 39°05'33" North, 94°25' West. For comparison, the modern GPS coordinates where the Kansas touches the the Missouri's right bank are 39°06'54" North, 94°36'36" West. If Ferdinand Hassler had been able to detect Lewis's errors, he could have shown the confluence to be only 10.5 statute miles west of its actual location. That would have been acceptable for a landmark such as this in 1804, or even at sea if a navigator were trying to find an island that rose, say, 250 feet above sea level. But if a ship's navigator had to stay clear of hidden reefs at the same coordinates, this much error could be disastrous. Similarly, the geographical uncertainties reflected in this jumble of coordinates would be utterly unacceptable today. At the very least, land ownership would be a shambles, and it would be possible to land an airplane only under Visual Flight Regulations at either of the Kansas Cities.

These charts, then, show the magnitude of uncertainty in geographical thinking—understanding and misunderstanding—that prevailed during the early 19th century, and that remained to be resolved. Thomas Jefferson believed, to the end of his life, that it was imperative to have an absolutely accurate map of Louisiana, beginning with the Missouri River. Surely, one feels, with a little more effort and influence on his part he could have had what he wanted before 1814. It finally came to pass, however, with the building of transcontinental railroads after 1850, which required precise surveys based on exacting celestial observations and calculations.