During the latter half of the eighteenth century, English, Spanish, and American explorers replaced their French counterparts as the leaders of exploration in the Mississippi and Missouri river valleys. As before, sensational accounts of western voyages continued to generate interest in the region. Widely read works by Le Page du Pratz, Robert Rogers, and Jonathan Carver enriched the tradition of popular reporting about the region. Increasingly, however, improved scientific methods of surveying, cartography, and natural description allowed for a more accurate picture of the West. By the end of the century the exact latitudes and longitudes of several important points in the West had been determined. The latest maps and journals of the explorers and cartographers influenced significantly the planning of the Lewis and Clark Expedition.

The exploration of the Missouri and Missisippi valleys proceeded slowly after the French ceded Louisiana to Spain in 1764. In fact, after Bourgmont’s expedition in 1714, no European successfully ascended the Missouri River much beyond the Platte River until Jacques D’Eglise reached the Mandan Indian villages in 1790. D’Eglise brought back stories of incursions by English traders into upper Louisiana from Canada. Alarmed at these threats to its sovereignty in the region, Spain took steps to promote the exploration of the upper Missouri River. In 1793, the Spanish chartered a “Company of Discoverers and Explorers of the Missouri,” or Missouri Company, to exploit the fur trade on the upper Missouri. They also offered a prize to the first Spanish subject to reach the Pacific Ocean via the Missouri River. The Spanish sponsored separate expeditions to the Mandan villages by Jean Baptiste Truteau, Antoine Simon Lecuyer de la JonchŠre, and James Mackay in 1794 and 1795. Finally, in 1796, a party sent by Mackay under John Evans succeeded in reaching those villages.

In the lore of American exploration, the idea of finding a great river leading from the Pacific coast into the interior of the continent never lost currency. Mapmakers had long postulated a great “River of the West”—or “Oregan River” as it was also called. Martin d’Aguilar of Spain was probably the first European to see the Columbia River in 1603, but his claims remained unsubstantiated for nearly 175 years. Another Spaniard, Bruno de Hezeta, upon reaching turbulent waters along the Northwest coast in 1775 said: “These currents and eddies of water cause me to believe that the place is the mouth of some great river, or of some passage to another sea.” And yet the river still proved elusive. The greatest English explorer of all, Captain James Cook, missed the Columbia River entirely during his voyages along the West coast in 1778.

Although Captain Cook failed to find the Columbia River, his voyage to the Pacific Northwest was not without bold ramifications for the exploration and development of the West coast. Cook determined the width of the North American continent by means of astronomical observations. He also discovered a very profitable sea otter trade. This sea otter trade sparked a heated competition among England, Spain, France, Russia, and the newly independent United States for a foothold on the West coast. In 1785, the king of France sent his country’s famous sea hero, Jean-Fran‡ois de Galaup, comte de La P‚rouse, to explore the Pacific coast of America and reconnoiter a site for a possible fur trading post. George Vancouver and Alexander Mackenzie, representing Britain, and Robert Gray of the United States explored the Pacific Northwest shortly thereafter. Before 1800 the Northwest coastline had been surveyed and mapped.

Meanwhile, in Canada, some independent traders who later organized as the North West Company pushed westward to preclude the involvement of the Hudson Bay’s Company in the fur trade in western Canada. Finally, in 1793, Alexander Mackenzie, a member of the North West Company, reached the Pacific Ocean via a half-mile portage over the Continental Divide. In 1798 David Thompson, a cartographer with the North West Company, mapped part of the upper Missouri for the first time and determined the latitude and longitude of the Great Bend of the Missouri (see Item 29).

This surge in exploratory activity provided considerable new geographic information on the Missouri and Columbia river basins. Though the explorations of the late 1700s were primarily motivated by commercial and nationalistic concerns, they also renewed interest in a route to the Pacific and in geographical theories such as symmetrical geography, pyramidal height-of-land, and the continental divide.

Perhaps no American felt this romantic yearning for the West more powerfully than Thomas Jefferson. Jefferson had grown up in a social circle where the men had planned an expedition to the Pacific. Since he shared his father’s avid interest in cartography, it is not surprising that he followed the reports of the explorations of the late 1700s very closely and collected many of the new publications and maps. Indeed, Thomas Jefferson himself promoted three unsuccessful attempts to find a route to the Pacific: in 1783 by George Rogers Clark (the brother of William Clark); in 1787-88 by John Ledyard; and in 1793 by Andr‚ Michaux.

In the summer of 1802, Jefferson, now president of the United States, read Mackenzie’s account of his journey to the Pacific. Mackenzie’s recommendation that the British government assume control of the Columbia River troubled Jefferson, who feared for the national interest if the British appropriated the West coast and all avenues inland from it for themselves. In response, Jefferson organized a new effort toward the Pacific. After Congress approved his plan of an expedition in February of 1803, Jefferson appointed his secretary Meriwether Lewis to lead the new exploring party, later known as the “Corps of Discovery.” Meriwether Lewis, who had firsthand knowledge of the western frontier from his military experience, was an Albemarle County neighbor of Thomas Jefferson. Lewis’s grandfather, Thomas Meriwether, and Jefferson’s father had each been members of the Loyal Company. In 1803 Jefferson dispatched Lewis north to Pennsylvania to make arrangements for the expedition and to augment his training in geography and cartography. Both Jefferson and Lewis realized this training was vital, since the expedition would offer an unprecedented chance to bring back data on the geography of the western half of the American continent. Thus, before commencing the expedition, Lewis learned how to make celestial observations from Robert Patterson, a mathematician, and Andrew Ellicott, the foremost American geographer and surveyor of his day.

In August 1803 Lewis set off down the Ohio River from Pittsburgh and stopped at Louisville, Kentucky, to see his friend and newly appointed expedition co-captain, William Clark. Lewis carried various accounts and maps of the West with him, including geographical works by Arrowsmith, Mackenzie, Vancouver, Thompson, and Le Page du Pratz as well as reference books and astronomical tables for the longitudinal calculations he would have to make. At some point he received a new map that Secretary of Treasury Albert Gallatin had commissioned from Nicholas King expressly for the expedition (Item 31).

While at Camp Dubois near St. Louis during the winter of 1804, Lewis and Clark obtained maps by James Mackay and Antoine Soulard, a series of route maps by John Evans, excerpts from Jean Baptiste Truteau’s journal, and the journal of Mackay and Evans. Lewis spent a great deal of time in and around St. Louis talking to Indian traders who had knowledge of the Missouri River. That same winter, in addition to his many other duties, Clark, an experienced surveyor, taught himself how to use the sextant and the octant that Lewis had acquired for the expedition. Clark, in fact, performed most of the mapping duties for the expedition.

Both Meriwether Lewis and William Clark continued to learn about the topography of the West from Indians and traders as they ascended the Missouri River throughout 1804 and at their winter camp near the Mandan villages. Like other explorers before them, they made extensive use of Indian maps, which were drawn on animal skins or sketched from scratchings in the dirt.

This section of the exhibition will focus on the explorations and maps of the West in the period immediately preceding the departure of Meriwether Lewis from the East in 1803. Geographic information from British, French, and American explorations in the West and along the Pacific coast influenced directly Thomas Jefferson’s planning of the Lewis and Clark Expedition. Because the results of the Spanish-sponsored explorations of the 1790s were little known to Jefferson at the time, those results are not included in the exhibition. Two final items in this section show the results of the Lewis and Clark Expedition: William Clark’s map of 1810 (Item 32) and the 1814 published journals of the expedition which include an engraved version of Clark’s map (Item 33).

“A Map of the British and French Dominions in North America with the Roads, Distances, Limits, and Extent of the Settlements.” 1755.

“A Map of Louisiana, with the course of the Missisipi.”
In The History of Louisiana, or of the western parts of Virginia and Carolina. London, 1763.

A Concise Account of North America. London, 1765.

“A New Map of North America From the Latest Discoveries.”
In Travels Through the Interior Parts of North America in the Years 1766, 1767, and 1768. London, 1781.

“Chart of the NW Coast of America and NE Coast of Asia explored in the years 1778 and 1779.”
In A Voyage to the Pacific Ocean. London, 1784.

“A Chart Shewing Part of the Coast of N.W. America.”
In A Voyage of discovery to the North Pacific ocean, and Round the World. London, 1798.

“A Map of America between Latitudes 40 and 70 North, and Longitudes 45 and 180 West, Exhibiting Mackenzie’s Track.”
In Voyages from Montreal, on the River St. Laurence, through the Continent of North America to the Frozen and Pacific Oceans; In the Years 1789 and 1793. London, 1801.

“Map of the Mississippi River.”
In The Journal of Andrew Ellicott. Philadelphia, 1803.

“A map showing the Great Bend of the Missouri.” 1798.

“A Map Exhibiting all the New Discoveries in the Interior Parts of North America.” 1795, with additions to 1811.

“Map of the western part of North America.” 1803.

Facsimile of “A Map of part of the Continent of North America.” 1810.

33. 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 . . . . Paul Allen, editor. Philadelphia, 1814.

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