Over 200 years ago, two soldiers, Captain Meriwether Lewis and his friend Second Lieutenant William Clark, began a journey that would change the course of history forever. Sent on an expedition by the third president of the United States, Thomas Jefferson, these two men, along with over forty U.S. Army and civilian volunteers, explored the vast expanse of territory that was the West.

The Lewis and Clark Expedition, or the Corps of Discovery Expedition as it was called, possesses a historical significance that cannot be forgotten. It was this journey that was the first to scientifically explore the region’s topography, flora, and fauna, as well as to create maps.

Cartography in the new country called the United States of America was a vital part of the country’s expansion and trade development. Before the expedition, any maps of the area west of the Missouri River were either primitive, rare, or nonexistent. As they explored new territories, Lewis and Clark mapped out these uncharted lands using information from Native Americans and traders, along with compasses, an octant, rods, chains, telescopes, a chronometer, and other simple tools. When they returned, they were able to provide President Jefferson and the nation with maps, journals with descriptions of what they saw, and seven live animals.

The expedition was long and arduous, and taking one look at a map of the Lewis and Clark Expedition will help you understand why, for these explorers traveled more than 8,000 miles on foot, horseback, and by simple canoes. Understanding this expedition is best done by tracing their journey on a map and reliving their experiences at each location along the way.

Mapping the Unknown: Preparation and Departure

Since the 1780s, Thomas Jefferson had been contemplating the possibility of a journey to the Pacific Northwest to establish trade routes and explore the area. It wasn’t until 1803, however, that Jefferson, now President of the United States, was able to commission an expedition for this purpose.

Planning the Expedition

Having recently purchased the Louisiana Territory from Napoleon Bonaparte, which comprised 828,000 square miles, Thomas Jefferson requested funds from Congress for an expedition to explore this new territory and reach the Pacific Ocean. With these funds, he commissioned the Corps of Discovery and chose Captain Lewis as its leader.

For the next several months, Lewis, who chose Clark as his co-leader, commenced work on the various expedition planning tasks. Lewis was sent to study medicine, astronomy, navigation, animal and plant preservation, latitude and longitude computation, and paleontology.

Supplies were also built and gathered during this time. Their keelboat was constructed, and they carried with them one Newfoundland dog called Seaman, who completed the entire journey with them, along with advanced weapons, blacksmith supplies, cartography equipment, flags, medicines, gift bundles, and the essential supplies necessary for the trip.

Their route was to take them up the Missouri River from St. Louis to the Rocky Mountains and thence to the Columbia River and the Pacific Ocean.

Departure from St. Louis

On May 14, 1804, Clark and the Corp of Discovery made their way on the Missouri River from Camp Dubois in Illinois to St. Louis, Missouri, in six days of traveling. Here, Lewis and several others joined the group. The Lewis and Clark Expedition made their official departure on the 21st of May, and they wouldn’t return for two and a half years.

Traveling by their keelboat and two small canoes, the party of over forty explorers set sail. Passing through what is now Kansas City, Missouri, and Omaha, Nebraska, they reached what is today called Sioux City, Iowa, where the only member of the expedition to die during the trip breathed his last and was buried. On the last week of August 1804, the party arrived at the edge of the Great Plains.

Mapping the West: Exploring New Territories

In these uncharted territories, Lewis and Clark had only a faint idea of what to expect. Reaching the Great Plains, which encompasses a vast area west of the Mississippi River and east of the Rocky Mountains, they encountered a place abounding in animal life, including countless herds of bison.

Traveling further into the Plains, the Corps of Discovery met many Native American tribes, which were only a few of the nations they established relations with throughout the entire journey.

Encounter with Native American Tribes

Meeting the Sioux and Mandan Tribes

In September 1804, the Lewis and Clark Expedition was traveling along the Missouri River in what is now present-day South Dakota. While they would end up meeting dozens of Native American tribes throughout the journey, at this point in their travels, they encountered the Sioux, who were known for being aggressive and warlike.

On September 25th, there was a confrontation between the Corps and the Sioux, specifically the Lakota nation, in which the chiefs demanded tribute for the expedition’s use of the river. Lewis offered the chiefs gifts first, but this cultural misunderstanding led to near violence when several warriors grabbed one of the expedition’s boats. Lewis and Clark and their fellow travelers presented arms, and one chief, Black Buffalo, ordered his warriors to stand down. The situation was resolved with better gifts, including tobacco and whiskey, and the expedition was allowed to continue without further incident. Similar cultural interactions occurred at other times during the journey, but violence was averted with gifts.

Throughout the expedition, Lewis and Clark made many notes and observations regarding the cultural practices of each tribe. They also established trade relationships with many different nations, including the Mandan tribe.

During the winter of 1804, the Corps built Fort Mandan, which is in present-day North Dakota. Here, they spent the winter in close contact with the Mandan tribe and met a French-Canadian fur trapper named Toussaint Charbonneau and his Shoshone wife, Sacagawea.

Sacagawea’s Role and Contributions

Sacagawea played an influential role in the Lewis and Clark Expedition. In February 1805, she gave birth to a baby son while staying at Fort Mandan. Her husband, Charbonneau, wished to join the Corps, and Sacagawea was to come as well. To ensure Sacagawea was well enough to join the group, the party remained at Fort Mandan after the winter had come to an end. At last, the expedition was ready to set off from Fort Mandan for the final leg of the journey on April 7, 1805.

Sacagawea acted as both a guide and interpreter on the trip. While she was not the primary guide, she was a great help with her knowledge of the Idaho and Montana areas, and her presence as a woman with her child on her back eased tensions with other Native tribes, as they saw that the expedition was a peaceful one. Additionally, her knowledge of the Shoshone and Hidatsa languages was essential for interpreting and communicating with other tribes. Sacagewea also proved invaluable to the party for her ability to find edible plants to supplement their store of supplies.

Geographic Discoveries

Mapping the Missouri River

As they traveled along the Missouri River north and due west, the Corps of Discovery made their way through what is today called Montana. On the journey there, they made observations and notes regarding the landmarks and obstacles they encountered.

Among these major landmarks that were unmentioned in a prior explorer’s description of the route were the Rocky Mountains. Because this was left out, Lewis and Clark believed they could carry boats from the Missouri River to the Columbia River, for they did not know that they had to cross these mountains.

Another notable landmark was the Great Falls of the Missouri River, which is located in central Montana.

Every day, Clark made immensely detailed notes and maps of these, and many other landmarks, and the river’s course and features. He revised and updated these maps continually so that, when he returned, the world had the most accurate maps of the area yet made.

Reaching the Pacific Ocean

By September 1805, the expedition had crossed Lemhi Pass and was making their way down the mountains by way of the Clearwater River and the Snake River in what is now Idaho. Soon, they reached the Columbia River, which marked the last river on their journey to the Pacific Ocean.

Traveling along the Columbia River, past Celilo Falls and today’s Portland, Oregon, the Corps sighted the Pacific Ocean for the first time on November 7, 1805. They arrived two weeks later and set up camp on the north side of the Columbia.

Their choice of campsite was unfortunate, for it was frequently hit by storms, and they lacked food. Exploration of the area led to a belief that the south side of the river would be a better location for their camp. By popular vote on November 24, 1805, they moved to the south side, near what is now Astoria, Oregon. Here, they built Fort Clatsop and remained there through the winter of 1805.

Mapping Their Way Back: The Return Journey

During the winter, Lewis and Clark spent their days writing and documenting all that they had seen during the expedition. From filling journals with botanical information to practicing cartography, they wasted no time.

Challenges and Hardships

Harsh Winter Conditions

At Fort Clatsop, the winter conditions were difficult for the members of the expedition. With limited resources, the Corps was forced to make nearly daily hunting and gathering trips just to have enough food for survival.

The weather was a typical Pacific coast winter, with cold, fog, and lots of rain. Because of this, many of the explorers suffered from colds, influenza, and rheumatism. Moreover, their furs and hides were damp for so long that they rotted and were infested with vermin.

Anxious to return at the earliest opportunity, the Lewis and Clark Expedition set out for home on March 23, 1806, as soon as the weather permitted it.

Negotiating with Native American Tribes

For the first leg of the journey home, the expedition took the same route as the way they had come, namely by the Columbia River. Soon, they reached the Rocky Mountains, but the mountains were still covered with snow, so they waited for it to melt.

On April 11, 1806, while waiting, Seaman, Lewis’s dog, was stolen by one of the nearby Native American tribes. The Corps was able to find the dog, and no violence occurred because of the incident. Of all the conflicts with Native American tribes on the trip, most were resolved with diplomacy. Whether by giving gifts or explaining the situation, tense atmospheres were calmed without violence.

After crossing the Rocky Mountains, Lewis and Clark split up into two camps. Lewis went north to explore the Marias River, while Clark went south via the Yellowstone River. After making their way along these rivers separately, where both parties met with conflicts with Native American tribes, on August 11, 1806, they met up again at the confluence of the Yellowstone and Missouri Rivers. The Lewis and Clark Expedition made their way home by way of the Missouri River and reached St. Louis on September 23, 1806.

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