The trail that led Lewis and Clark to the Columbia River in 1805 began with international political intrigue five years earlier and the prescience of President Thomas Jefferson, who shrewdly exploited the strengths and weaknesses of three European nations that claimed portions of the American continent. To his everlasting credit, Jefferson understood that unless the fledgling United States acquired Louisiana and joined the race to claim the Pacific coast, the nation might never expand west beyond the Mississippi River.

In October 1800, France and Spain signed the secret Treaty of Ildefonso. In it, Napoleon forced Spain to restore to France the Louisiana country, the vast region west of the Mississippi that Spain had acquired in the 1763 Treaty of Paris.

In the spring of the next year, 1801, Napoleon sent soldiers to the West Indies, apparently in preparation for a military occupation of Louisiana. Jefferson, who was inaugurated president in March of that year, worried that he would lose the region to either France, from the south, or to Great Britain, whose traders were making inroads on the upper Mississippi from trading posts in the Hudson Bay drainage to the north. Jefferson accelerated his plans for an American expedition to the West, and undoubtedly was relieved to learn that Napoleon’s army had suffered a disastrous epidemic of yellow fever in the Indies, an epidemic that crushed any chance of an occupation.

Historian David Lavender suggests it was this knowledge that prompted Jefferson to instruct his minister to France, Robert Livingston, to begin negotiations for an American purchase of Louisiana. Later, Jefferson sent James Monroe to France to assist Livingston. Meanwhile, Jefferson approached the Spanish minister in Washington, the Marques de Casa Yrujo, for permission to send a small expedition west beyond the Mississippi into territory that Spain continued to claim publicly but had not occupied beyond its missions in California. Although rebuffed by Casa Yrujo, Jefferson knew about the secret treaty, and he also knew that France had forced Spain to give up Louisiana the previous October. His approach to the Spaniard was for show only.

In 1803, France offered to sell Louisiana to the United States. The offer came as a surprise, although the previous year Jefferson had directed his minister in Paris to ask Napoleon to sell New Orleans to the United States. But the whole of Louisiana was more than Jefferson could have hoped for. Jefferson wanted to keep the French out of the Mississippi Valley and ensure untroubled access to New Orleans. Napoleon needed cash to finance his wars in Europe, and it was a safe bet he could not simultaneously wage war in Europe and hold onto his newly acquired territory across the Atlantic Ocean. Jefferson was delighted. For $15 million, he more than doubled the size of the United States and resolved an issue that could have led to war with France over New Orleans. The United States purchased more than 827,000 square miles of land, stretching from New Orleans to the Continental Divide of the Rocky Mountains.

This was the Louisiana Purchase. The United States would not take possession until December, but in January, several months before the sale had been offered or accepted, when the land still was owned by France and administered by Spain (native land claims, of course, were not part of the equation at the time), Jefferson sent a secret message to Congress proposing the expedition that would be led by Lewis and Clark to explore the land west of the Mississippi River. The South, where Napoleon might establish a foothold at New Orleans, was one problem for Jefferson. The West, where the British might do the same thing, was another problem. The French in the South and the British in the West were potential threats to America’s national security.

Jefferson sought to deal with both threats simultaneously. He needed to better understand the West. Spain considered the mission a threat to its sovereignty and refused to grant passports for the expedition. But the matter was moot because Spain had ceded the territory to France. Despite Spain’s objection, Jefferson believed the expedition would be small enough and would travel far enough north of Spanish settlements that it would not be considered a threat. He also knew that the British controlled the fur trade west of the Mississippi and north into present-day Canada. Great Britain granted passports for the expedition, as did France.

Britain was Jefferson’s chief concern. Alexander Mackenzie had been to the Pacific and back in the early 1790s, the first European to connect the Pacific coast with the interior plains. Jefferson knew about Mackenzie’s accomplishment. But Jefferson also knew how difficult the journey had been, and he theorized that the most practicable route between the plains and the Pacific lay farther south than the torturous route Mackenzie took down the Tacoutche-Tesse, later named the Fraser, up the Blackwater and down the Bella Coola rivers to salt water. Jefferson knew that Gray’s discovery of the Columbia River in 1792, one year before Mackenzie reached salt water a couple hundred miles to the north, gave America a prior claim to the Columbia, but the American position would be solidified by an expedition that would discover a land route from the headwaters of the Missouri to the Columbia.

Mackenzie, meanwhile, published a book about his adventures in 1801. In the book, he recognized the importance of the Columbia to the westward expansion of European civilization: “Whatever course may be taken from the Atlantic,” he wrote, “the Columbia is the line of communication from the Pacific Ocean . . .the most northern situation fit for colonization, and suitable to the residence of a civilized people.”
Publicly, Jefferson’s intent for the cross-country exploration was to enhance geographic knowledge of the West. Privately he aimed to expand the United States and wrest the fur trade from the British. In his January 1803 request to Congress for $2,500 to finance the expedition, he couched his intent in terms of promoting commerce, which was within the powers granted Congress in the Constitution. He wrote that the Indians of the Missouri River drainage supplied furs “to the trade of another nation”—-an obvious reference to Great Britain—-and that the United States would do well to know these tribes better. He theorized that the Missouri might provide a better transportation route to the Pacific for this commerce.

Thus through westward expansion, the United States would usurp the fur trade from Great Britain. Jefferson wrote, in part: “. . .The interests of commerce place the principal object within the constitutional powers and care of Congress, and that it should accidentally advance the geographical knowledge of our own continent can not but be an additional gratification.”

A month before his March 1801 inauguration, Jefferson had appointed Meriwether Lewis, then 26, his personal secretary. It appears, although this is a matter of dispute among historians, that Jefferson had been grooming Lewis for command of the expedition ever since. In his June 20, 1803, instructions to Lewis regarding the exploration, Jefferson wrote:

The object of your mission is to explore the Missouri River, and such principal stream of it, as, by its course and communication with the waters of the Pacific Ocean, whether the Columbia, Oragan [sic], Colorado, or any other river, may offer the most direct and practicable water-communication across the continent, for the purposes of commerce.”

The Columbia, as Lewis and Clark discovered, is not a principal stream of the Missouri. That did not matter. The goal was not the headwaters of the Missouri but the Pacific Ocean. Bernard DeVoto believes Jefferson already had decided to send an exploratory mission west across then-Spanish Louisiana when he took office in 1801. To the expansionist Jefferson, the exploration would knit together the eastern and western ends of the American continent, if tenuously.

Louisiana had been Spanish, then French, and soon would be American, thanks to the $15 million Louisiana Purchase. But Louisiana ended at the Continental Divide. The land west of the divide, where the mostly unknown Columbia drained to the Pacific, was unclaimed by Euro-Americans, variously and sometimes vigorously or vaguely claimed by the United States and Great Britain, based on the explorations of Robert Gray and George Vancouver in 1793. In 1803, the matter was unresolved, and Jefferson believed a land expedition to the Columbia would help solidify America’s claim. An astute geopolitical thinker, Jefferson intended that the West would be American; and the first step was to find a water route across Louisiana to the Pacific. If this was imperialism, it was a uniquely American brand of it, DeVoto writes: “The dispatch of the Lewis and Clark expedition was an act of imperial policy. Even while he moved to buy New Orleans the President of the United States was moving to possess Louisiana.”

Jefferson wanted to supplant the British from the fur trade on the vast plains between the Mississippi and the Continental Divide, and he wanted to beat the British overland to the Pacific. As Jefferson and Lewis planned the expedition, the North West Company, a Canadian, and therefore British, fur company was making its own plans to push west across the divide into the Columbia River Basin. In fact, David Thompson’s first expedition across the Rockies into the Canadian Columbia River Basin would occur in just three years — while Lewis and Clark were westbound on the Missouri. The race was on to fully claim the Columbia River and its lucrative fur trade, and also to absorb the fabulous country into one nation or the other.