The Lure of the Columbia
David Thompson's career in the fur trade soon gravitated west from Hudson Bay. In 1787, Bay Company officials assigned him to a small party that traveled to Lake Winnipeg and up the Saskatchewan River all the way to the foothills of the Rocky Mountains, where they wintered with a large camp of Piegan (Pikani or Pikuni) Blackfeet. The teenaged Thompson spent his months in the tent of an elder named Saukamappee, who spoke Cree and had survived the 1780-81 smallpox pandemic. From Saukamappee, Thompson absorbed Blackfeet culture and heard stories that stretched back to the days before horses and guns. But the boy also saw into the future, forming relationships with young tribal leaders who would interact with both British and American interests during the first decade of the next century.
Thompson's First Surveys
Two winters later, posted on the North Fork of the Saskatchewan River, Thompson suffered a leg fracture that laid him up for most of the next year. He spent an eight-month convalescence rediscovering his math skills and learning cartography from professional surveyor Philip Turnor. Thompson's first surviving map, drawn during his canoe trip back to Hudson Bay during the last year of his apprenticeship, showed promise that the company encouraged.
In 1792, while David Thompson searched for a northerly route from Hudson Bay to the rich fur grounds around Lake Athabasca, Thomas Jefferson attempted to mount a western exploring expedition led by the French botanist Andre Micheaux. That spring, the American captain Robert Gray described the mouth of the Columbia River, and George Vancouver's lieutenant William Broughton surveyed the first one hundred miles of the river upstream, to a point just past modern Portland. In December, a party of Kootenai Indians left the source lakes of the Columbia River and crossed the Rocky Mountains on an ancient trail to meet Piegan Blackfeet associates for a session of gaming and trading. The Blackfeet brought along a Hudson's Bay Company clerk named Peter Fidler, who had trained in surveying with David Thompson under Philip Turnor. This meeting marked the first recorded contact of furmen with a Columbia Plateau tribe, and the beginning of a Kootenai connection that would color the way David Thompson experienced the upper Columbia, Kootenai, and Clark Fork/Flathead/Pend Oreille drainages.
In 1793, Alexander Mackenzie made his historic crossing of the continent, moving from the Peace River drainage across an easy portage to the Parsnip and Fraser Rivers. Mackenzie thought he was on the Columbia, the Great River of the West; although he broke off the main stem to follow a tribal trail to the Pacific at Bella Coola, he assumed that he had found the key to a practical trade route. At that time, Mackenzie was working for the North West Company, the aggressive and bitter rival of the Hudson's Bay. When he described his journey and visualized the prospects for transcontinental trade, the news buzzed through the fur trade world and beyond. Thomas Jefferson ordered a copy of Mackenzie's book as soon as it was published, and also made sure he obtained London cartographer Aaron Arrowsmith's latest North American map, which included coordinates from fur trade surveyors like young David Thompson.
The Bend of the Missouri
In the spring of 1797, David Thompson defected from the Hudson's Bay to the rival North West Company. At North West's Grand Portage supply depot on Lake Superior for summer meetings, the company's new surveyor met managing partners from Montreal and "wintering partners" who worked in the field. They presented Thompson with a grand challenge of navigation and business that involved visiting various company posts beyond Lake Winnipeg to determine their exact coordinates, then moving south on the Red River to visit the cluster of Mandan-Hidatsa-Arikara villages on the Missouri River, in what is now North Dakota. Part of Thompson's instruction, which sounded almost like a nod to mammoth and fossil enthusiast Thomas Jefferson, was to bring back any large bones that he might run across.
Thompson began the assignment by assembling a crew of French-Canadian voyageurs — French would be his everyday work language for the next 15 years. With their help, he fashioned sledges to haul trade goods and bartered for sled dogs with Lake Winnipeg tribes. Traveling at a steady pace no matter what the conditions, he charted the coordinates of several posts in the Assiniboine River country, then made a Christmas dash to the Mandan villages. Thompson remained there long enough to record considerable information about the cultures and local landscape before working his way east through the headwaters of the Mississippi drainage, eventually postulating that a lake in northern Minnesota was the true source of that river. Although his nomination proved to be a few miles off, Thompson did establish that the Mississippi rose south of the 49th parallel, which had far-reaching effects on the North West Company's trade network.1 When Thompson rendezvoused with company partners for the 1798 summer meetings at Grand Portage, Alexander Mackenzie reckoned that their new surveyor had accomplished two years work in ten months. Excepting that Thompson had failed to find any mammoth relics, his first expedition for the Nor'Westers was marked as a great success.
"Bend of the Missouri River"
Upon the completion of his journey, Thompson created a map that he called "Bend of the Missouri River." Drawing on his own sextant work, the chart supplied the first accurate longitude for the Mandan villages at the confluence of the Knife River. The mapmaker marked each settlement in the cluster by tribe and dwelling type, and included a census of adult males. He delineated stream flow with delicate feather arrows, followed major tributaries upstream far enough to give shape to the drainage, and included topographical features such as the Turtle Hills. Many of the map's details relied on carefully gathered tribal information.
Thompson's "Bend of the Missouri" found its way from the British envoy in eastern Canada to Jefferson's Treasury Secretary Albert Gallatin, who delivered it into the hands of the President. Jefferson himself penciled a note on the map reiterating the coordinates figured by "Mr. Thomson Astronomer to the N.W. Company in 1798." On the back of the chart another note reads "A sketch of the North Bend of Missouri. This belongs to Capn. Lewis."
1. David G. Malaher, "David Thompson's Surveys of the Missouri/Mississippi in 1797-98." Paper presented to the 9th North American Fur Trade Conference & Ruperts Land Colloquium, St. Louis, Missouri, May 25, 2006.
Funded in part by a grant from the National Park Service, Challenge Cost Share Program.