How Lewis and Clark Worked

Lewis and Clark Image Gallery Sunset in Oregon, about where Lewis and Clark first laid eyes on the Pacific Ocean. See pictures of Lewis and Clark.
Jeff Olson/National Park Service

Exploration and discovery have been a part of the American experience since the land was first discovered by Europeans in the late 1400s -- we're a nation obsessed with adventure and adventurers. And no expedition of discovery has helped to shape the United States quite like the one led by Meriwether Lewis and William Clark, who set out in 1803 to find an all-water route to the Pacific Ocean.

The purchase of the Louisiana Territory that year had opened vast lands for Americans to settle. Under orders from President Thomas Jefferson, Lewis, Clark and their group of woodsmen, hunters, translators and boatmen -- "The Corps of Discovery" -- blazed a trail into the wilderness and traversed the continent for three years. Lewis shipped out of Pittsburgh on Aug. 31, 1803, and on Dec. 3, 1805, the party reached the Pacific, Clark's journal proclaiming "Ocian [sic] in view! O! The joy!" [source: Ocean in View]. The party ended their journey in St. Louis on Sept. 23, 1806.


The Corps didn't succeed in its primary objective of finding a river route all the way across the continent, but it was certainly successful in its other missions. The team meticulously mapped its route, identified plants and animals and opened up diplomatic relations with American Indian tribes. Its discoveries helped the nation understand its new size and assess the economic potential of the new territory.

Perhaps more importantly, the expedition also helped a new nation of people define themselves as adventurers. America could now be seen as a land of constant reinvention, a notion that persists in the psyche of its citizens to this day.

The Journey of Discovery

Thomas Jefferson was the brains behind the Lewis and Clark expedition.
Stock Montage/Hulton Archive/Getty Images

It was Thomas Jefferson's vision that enabled the journey of Lewis and Clark. He dreamed of discovering an all-water route through the continent to the Northwest Passage, the sea route through the Arctic Ocean that connects the Atlantic and Pacific Oceans. His prime motivation was to advance trade and settlement, and he started making preparations for an expedition as early as 1792. His strongest incentive for westward expansion came in 1802, after he heard of Alexander McKenzie's overland journey across Canada. Fearing that the British might gain control of the Western territories, Jefferson sought funding for an American expedition to the Pacific -- this, in turn, led to the Louisiana Purchase [source: University of Virginia].

On April 30, 1803, Jefferson signed the Louisiana Purchase, Treaty with France, undoubtedly the most important legacy of his presidency. He paid less than 3 cents an acre for the roughly 828,000-square-mile area, which doubled the size of the country [source: Encyclopedia Britannica]. The land stretched south from just above the Canadian border to New Orleans and the Gulf of Mexico, west to the Continental Divide in Colorado, and east to the Mississippi River. If it weren't for the Louisiana Purchase, the expedition of Lewis and Clark would not have been possible.


The Lewis and Clark Expedition

In 1803, Jefferson named his private secretary and fellow Virginian, 29-year-old Meriwether Lewis, as the commander of the Western expedition [source: University of Virginia]. Lewis (1774-1809), an accomplished sharpshooter and experienced outdoorsman, had served as an Army captain in the Northwest Territory. He chose William Clark (1770-1838), a friend from the Army, as his co-captain. Lewis felt that Clark possessed the right balance of physical strength and intellect to help lead a crew on an uncharted voyage of discovery -- and he also had a reputation as a mapmaker, so he became the official cartographer of the party. His final map of the Lewis and Clark Trail is accurate within 40 miles, though it spans a distance of 8,000 miles.

In his final instructions to the explorers, Jefferson stated that "…the object of your mission is to explore the Missouri River, and such principal streams of it, by its course and communication with the waters of the Columbia, Oregon, Colorado or any other river, may offer the most direct and practicable water communication across this continent for the purposes of commerce" [source: National Park Service].


A direct water route from sea to sea may have been Jefferson's main aim, but it wasn't his only goal for the expedition. Jefferson, like all Enlightenment thinkers, wanted to use science to shape the expedition. He told the explorers to collect, classify, document and observe the landscape, its wildlife and people with scientific precision. That's why there is such an abundance of information about the journey -- most of the members kept journals, took detailed notes and mapped the terrain as they went forward.

Because the expedition crew would most likely be running into American Indian tribes on their journey, Jefferson also wanted them to be fluent in the nuances of sign language, the rituals of diplomacy and the subtle symbols of military power. The men had to study up on the social mores of different tribes -- they had to know tribal hierarchy, how to behave properly in ritual ceremonies, which tribes were dangerous and which colors were sacred or offensive.

After months of preparation, it was time to set off. Lewis gathered a partial crew in Pittsburgh, Pa.

Lewis and Clark's Journey

Painting of Sacajawea with Lewis and Clark
Newell Convers Wyatt/Bridgeman Art Library/Getty Images

On Aug. 31, 1803, Lewis set out for St. Louis from Pittsburgh, Pa., with a crew of 13 men and one dog. On the way, they picked up Clark along the Ohio River. Pittsburgh, which was then known as the "Gateway to the West," was the perfect point of departure -- a bustling frontier town at the confluence of two rivers that was a large center of boat construction.

The time Lewis spent in Pittsburgh was filled with anxiety. The construction of the boat he had designed was delayed by six weeks, and he had trouble communicating with Clark. Adding to his tension was the news that weather conditions and falling water levels could delay his trip until the following spring. But Lewis hastened completion of the boat, and the group was able to set out on time. The expedition set up camp for the winter in the St. Louis area, where they awaited the legal transfer of the Louisiana Territory before they officially set out on May 21, 1804.




The size of the group traveling with the Corps of Discovery varied throughout the trip. Some members split off to explore other routes, some stayed with friendly tribes and some were picked up along the way. The official team, however, consisted of 33 people, 29 of whom were members of the Army. They earned between $5 and $8 per month for their services [source: Lewis and Clark Trail].

From St. Louis, the Corps of Discovery traveled northwest up the Missouri River to the Mandan Villages in what is now South Dakota. By following the Missouri they were able to forge through the Rocky Mountains, considered the most dangerous part of the trip because the Corps had no idea of its size. Once they crossed the Rockies, the group followed the Clearwater River to the Snake River, eventually coming to the Columbia River, which led them to their goal of the Pacific Ocean [source: PBS]. They had to drag their boats across the occasional valley, but for the most part they did follow a water route from east to west. However, it proved to be too dangerous and unmanageable for commercial endeavors.

After reaching the Pacific, the Corps set up Fort Clatsop, named for the tribe that inhabited that area west of the Columbia River in what is now Oregon. The group spent the winter there, started the return journey on March 23, 1806, and arrived back in St. Louis on Sept. 26 [source: National Geographic].­

Life on the Lewis and Clark Expedition

Beaverhead Rock near Dillon, Mont., the home of the Shoshone Indians
Photo courtesy National Park Service

The crew carried quite a load of supplies for the trip, totaling $2,324 [source: National Geographic]. In addition to the boats -- a 55-foot Keelboat and two pirogues (small open boats) -- the Corps brought two horses (they would later trade for more), 35 oars and a broad sail. They had all the camping supplies a party of this size would need, plus their cartographical instruments. They also thought to bring gifts for the Indians they encountered -- ivory combs, pocket mirrors, tobacco, hollowed-out tomahawks that doubled as pipes, and thread, bright cloth, scissors, beads and silk ribbons. And, of course, they stocked up on medicines like quinine, opium and mercury.

Amazingly, only one member of the expedition died on the long journey. Charles Floyd succumbed to "bilious colic" [source:], probably appendicitis, shortly after the expedition set out from St. Louis. But by the time the crew reached the Rocky Mountains, many members had been stricken with dysentery, malaria, venereal diseases (most commonly syphilis, contracted from unprotected sex with Indian women) and injuries.


The conditions were not terribly difficult in and of themselves -- complaints of extremely cold winters and long rains were most often cited in journals. But because of the newness of the situation, each unfamiliar condition presented new problems. The expedition was plagued, for example, by prickly pear cacti that littered the terrain and caused foot injuries. And there were bound to be a few accidents on an 8,000-mile journey. Most famously, Pierre Cruzatte, a master boatsman, translator and fiddler who was blind in one eye and nearsighted in the other, accidentally shot Lewis while hunting in 1806. There were also a number of boating injuries, falls from traversing craggy, wet, mountainous terrain, and accidents with axes and knives. Everyone in the party was injured at some point, but none so severely they weren't able to return home.


­Of the animals that the party encountered, some proved edible, like channel catfish, steelhead trout, deer, quail, goose and elk. Others, though, were much more fearsome. The Corps documented experiences with mountain lions, coyotes, snakes, bobcats, foxes and, most famously, bears. Lewis and Clark had never before seen a grizzly bear, and it took a couple of run-ins before they learned how to best handle the beasts. On May 5, 1805, Clark recalled spotting the largest bear he'd ever seen. He'd long hunted brown bears but had never dealt with a bear that can grow to more than 8 feet tall and 900 pounds. On seeing his first grizzly (about 600 pounds), Clark noted in his journal that the animal was "verry [sic] large ­and a terrible looking animal" [source: Canadian Geographic]. It took 10 shots by two party members to kill the bear.

The Corps came across almost 50 Indian tribes on their journey, notably the Shoshone, Nez Pierce, Crow and Cheyenne [source: National Geographic]. Some proved dangerous, but without others, like the Shoshone, the travelers would have been doomed.­

Lewis and Clark's Discoveries

Sacajawea interprets Lewis and Clark's intentions to the Chinook Indians.
MPI/Hulton Archive/Getty Images

Obviously, it could be contentious to say that Lewis and Clark's team actually discovered anything, because the Indians had been familiar with the flora and fauna of the West for centuries. But Lewis and Clark did bring a vast array of plants and animals to the attention of Americans in the East. The party was able to document more than 125 varieties of animals and 178 animal species that inhabited the newly acquired land [source: National Geographic]. Some of the plants proved quite useful to the often hungry travelers. In addition to new varieties of trees, grasses and flowers, they also documented new types of tobacco, herbs like hemlock and tarragon, and the blue huckleberry, California hazelnut and Cascade grape.

Lewis and Clark weren't the first to make the North American transcontinental voyage -- Indians had most likely been doing that sort of thing for centuries. And they had also been beaten to the punch by a Canadian expedition led by Alexander Mackenzie, which completed the trip in 1793.


So what was so important about their voyage?

Lewis and Clark's Historical Impact

Captain Clark and his men shooting bears.
Hulton Archive/Getty Images

The Corps of Discovery was the first American group to undertake the journey, and its impact can't be underestimated. The expedition introduced Americans ­and Europeans to hundreds of varieties of plants and animals, met with dozens of native tribes and produced an accurately mapped route to the Pacific Ocean -- and returned home safely. The group came to embody the values of manifest destiny, prodding other adventurers to embark on their own journeys of discovery and exploration.

The expedition opened up new territory for the fur and lumber trade and pointed out the best lands for future settlement and agriculture. It allowed a young country to blossom into greatness, because more land had equated to more resources and therefore, more power. The influence of the expedition is incalculable. For better or worse, there is no doubt that the expedition of Lewis and Clark forever changed the course of the country's history.


To learn more about the Lewis and Clark expedition, take a look at the links on the next page.


Lots More Information

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More Great Links

  • Encyclopedia Britannica. Louisiana Purchase.
  • Jhamandas, Asha. "Grisly Gods." Canadian Geographic, November-December 2003.
  • FAQs.
  • Members of the Corps of Discoveries.
  • Library of Congress: After Lewis & Clark.
  • Library of Congress: Lewis & Clark.
  • National Geographic: Lewis & Clark Discoveries: Animals.
  • National Geographic: Lewis & Clark Discoveries: Plants.
  • National Geographic: Lewis & Clark Discoveries: Tribes. tribe.html
  • National Geographic: Lewis & Clark Supplies.
  • Lewis & Clark: The Corps.
  • Lewis & Clark: The Equipment.
  • Sierra Club: Lewis & Clark Discoveries.
  • U.S. Army: Lewis & Clark Expedition: The Mission.
  • U.S. Army: Lewis & Clark Expedition: The People.
  • University of Pittsburgh: The Corps of Discovery.
  • University of Virginia: Medicine & Health on the Lewis & Clark Expedition. medical_history/lewis_clark/
  • University of Virginia: To the Western Ocean.