David Thompson concludes first scientific survey of the Columbia River and departs Kettle Falls for Montreal on April 22, 1812.

  • By Jack and Claire Nisbet
  • Posted 5/30/2010
  • HistoryLink.org Essay 9441
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On April 22, 1812, David Thompson (1770-1857), Canadian explorer, geographer, and fur trader, departs Kettle Falls and canoes upstream on the Columbia River, bound for eastern Canada. Thompson, a partner with the North West Company of Montreal, has recently completed the first scientific survey of the entire length of the Columbia and is retiring from the fur trade to compile a series of maps from the data he has collected on his journeys. His completed charts will include the first accurate rendition of the Inland Northwest north of the Snake River.

Tallying and Transporting Pelts

Late March of 1812 found David Thompson at Spokane House, the North West Company's headquarters for its Columbia District. Clerks and laborers at the fur post were busy tallying the pelts that had been collected by the company's agents on the Clark Fork, Pend Oreille, Kootenai, and Spokane drainages over the past year. When they completed the task, the total came to 122 packs weighing almost 11,000 pounds.  The Nor'Westers had only two cargo canoes on hand, and in order to transport this record harvest up the Columbia to the trail across Athabasca Pass, they would need four additional boats. Thompson, who had designed a series of cedar plank canoes, supervised the construction. 

On March 27, he departed Spokane House and rode north up the Colville Valley, noting "Cranes, Frogs & Rooks today ... Willows budding, Grass turning a lively green" (Thompson, Notebook 27). By April 1, he and a small crew had made camp on the banks of "Cedar Brook" (modern day Mill Creek, north of Colville in Stevens County).

Constructing Canoes

After felling trees from a nearby cedar grove and digging a nine-foot trough for soaking the boards, they began splitting timber for gunwales. While workers from Spokane House ferried loads of furs to Kettle Falls on horseback, Thompson directed his helpers in making the first two vessels, for which he was employing a "clinker built" style, shaving the top of each side board to a feather edge. Meanwhile, two voyageurs fanned out in search of birch trees, and Jaco Finlay (1768-1828), a clerk who had worked with Thompson for years, wrapped two frames with birch bark they found upriver, probably at Sheep Creek near present-day Northport. 

By the evening of April 21, Thompson's crew had carried the four new canoes seven miles to the top of Kettle Falls, where the two older canoes had been cached. After making sure that all the holes and seams were caulked with pine pitch, Thompson took out his sextant to observe for the latitude and longitude of the landmark he called Ilthkoyape Falls.   

At noon the next day, the six heavily laden canoes of the Columbia brigade cast off and paddled upstream. Among the fur packs, food casks, and baggage, Thompson packed a bundle of notebooks, which held a trove of geographic data he had collected during the past five years in the Columbia drainage. After ascending the Columbia to the mouth of the Canoe River, traversing Athabasca Pass, and descending the Athabasca River, Thompson delivered his final field report to the summer meeting of the North West Company at Fort William on Lake Superior. Forty-two years old, he announced his retirement from his long career as a "wintering partner" in the frontier fur trade. In recognition of his contribution as a geographer,  company officers offered to continue his salary for three years with the stipulation that he complete a set of maps for their use.

Making the Maps

In the fall of 1812, Thompson purchased a comfortable house in the village of Terrebonne, 30 miles outside Montreal. After settling in with his wife Charlotte and their children, he hired a carpenter to build a large pine table for map work and turned his focus to an epic cartographic project that he had been envisioning for many years. He laid out large sheets of linen paper, drew grids of latitude and longitude, and in April 1813 sketched a "hasty, rough map" (Thompson, Notebook 28A) of the territory he had explored west of the Continental Divide. This draft chart included a fictional "Caledonia River" flowing into Puget Sound (Thompson, "Remarks"). Long after Thompson had realized and corrected this mistake, London cartographer Aaron Arrowsmith included the nonexistent watercourse on the 1818 update of his esteemed series of maps of North America. 

As soon as that initial chart was sent to the director of the North West Company, Thompson began work on a more refined effort. He compiled meticulous tables for tracking surveys and astronomical observations, then transferred the raw numbers from his field notes into columns of organized data. He used his latitude and longitude readings to locate fixed points along watercourses and overland trails, filling in their sinuous courses according to the thousands of compass readings he had recorded. 

Over the next year, he continued work on two large maps depicting the North West Company's entire domain -- the first accurate depiction of the major drainages on both sides of the Continental Divide north of the 45th parallel. One of these charts, measuring 10 feet by 6 feet, is now mounted in the Archives of Ontario reading room in Toronto. On the southwest quadrant of this map, he noted part of Lewis and Clark's overland route with a dotted line, and included other information from a variety of sources.

During the coming years, after moving to Williamstown in Glengarry County, he continued to draw other maps of the Northwest, of different scales and styles. One of these, "Map of the Oregon Territory," measuring eight feet by seven feet, elegantly delineates the area between the Rockies and the Pacific. Large rivers and lakes are depicted in a robin's egg blue watercolor, the river deltas in a delicate buff. The lettering is meticulous and bold, but very spare; only watercourses and major mountains are labeled. 

A Remarkable Cartographer

In contrast, the 10 individual sheets of a "Map of North America from 84º West to the Pacific Ocean" and his "Map of North America from 110º West to the Pacific Ocean" bristle with information. Drawn on a scale of three inches and six inches to one degree of longitude, these charts detail the Kootenai, Clark Fork, Flathead, Pend Oreille, Spokane, Colville, and Palouse drainages where Thompson conducted the bulk of his Plateau explorations.

Tribal roads between the different drainages are denoted by dotted lines. Lewis and Clark's route is marked in yellow on one map and in blue on the other, winding down Lolo Pass to the Snake River's confluence with the Columbia. Remarks of interest are scattered across the sheets. He rendered the many waterways he had personally traveled with a high degree of accuracy. Away from these corridors, the quality of his work depended on his understanding of descriptions provided by local informants. But considering the conditions under which he conducted his surveys -- without an assistant, while occupied full-time as a fur trader -- his cartography is remarkably correct.

Sources: Jack Nisbet, The Mapmaker's Eye (Pullman: Washington State University Press, 2005); Jack Nisbet, Sources of the River (Seattle: Sasquatch Books, 1994); David Thompson, "Map of North America from 84º West to the Pacific Ocean," FO 925/4622, sheets 1-10, Public Record Office, Kew, England; David Thompson, "Map of North America from 110º West to the Pacific Ocean Collection," FO 925/4622, sheets 11-18, Public Record Office, Kew, England; David Thompson, "Map of the North-West Territory," Archives of Ontario, Toronto; David Thompson, "Map of the Oregon Territory," Add. Mss. P44,558 A, B, C, Map Room, British Library, London; David Thompson, "David Thompson, Notebook 27 and 28A, Archives of Ontario, Toronto; David Thompson, "Remarks on the Countries Westward of the Rocky Mountains, with References to the Rough Chart, by D. T., Terrebonne, 19 April 1813," Royal Commonwealth Society Library, Cambridge, England. See also Joann Roe, “David Thompson’s Columbia River: When Canada’s Master Surveyor Traveled the Length of the Great River of the West,” Columbia: The Magazine of Northwest History Vol. 24, No. 4 (Winter 2010-11), 27-29.

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