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The Lewis and Clark Expedition: How the USA Discovered Its Eventual Western Borders

The size of the United States changed dramatically in 1803 with the Louisiana purchase. The sale of the French-controlled territories, which stretched from New Orleans in the south to the border of Canada, measured some 2,140,000 km sq (828,000 sq mi) and nearly doubled the size of the young United States – and all for just $15 million, equal to around $315 million today. 

There was however a slight catch. The French had direct control over only a small fraction of this land, with much of it inhabited by Native American tribes. Whatsmore, the French had only begun to scratch the surface of this vast area with much of it almost completely unexplored by Europeans or Americans. 

Soon after the purchase, a decision was made by President Thomas Jefferson to send out an expedition that would map the new territories all the way to the Pacific Ocean. Placed in charge were two men whose names have gone down in American folklore, Captain Meriwether Lewis and Second Lieutenant William Clark. Their two-year journey was officially named the Corps of Discovery Expedition, but we know it better as the Lewis and Clark Expedition.     


The Emperor Napoleon
in His Study at the Tuileries

France had controlled this area from 1699 until 1762 when it was ceded to Spain. However, in 1800, France regained control of the territory with the hope of establishing a broader French Empire in the area. That didn’t last long and just three years later, with the spectre of war with England looming, Napoleon decided to cut his losses with the North American territory.  

You might expect that the American population would have been over the moon to be told that their country was now nearly twice the size, but that wasn’t quite the case. On the surface much of the opposition coming from the Federalist party was concerned with the legality of it all and whether the territory still belonged to Spain, as the Spanish claimed. In reality, many of their concerns came down to economic self-interest. They were worried about the economic knock-on such a large expansion would have on the traditional New England states of the Northeast. The addition of ports in the south (and eventually the west) would mean a rivalry with those in the East. This was such an issue that a vote was brought to Congress to block the purchase, but it failed by just two votes.

The Purpose

Jefferson believed that one of the best ways to sure-up support for the new purchase was to commission a grand expedition to set forth and explore the new territory. He probably rightly assumed that one of placating a restless population was through adventure and a greater understanding of what lay to the west. After all, humans do love to dream about distant possibilities.  

Mapping the area and laying some kind of claim before those greedy Europeans came back was also high on his list, as was furthering the general scientific understanding by studying plants, animal life, and geography, while also expanding possible economic avenues by establishing trade with the local tribes. 

Jefferson, and just about everybody else at the time, was particularly interested in finding the elusive Northwest Passage to the Pacific Ocean. Many had assumed for quite a while that there must be a connection between the Atlantic and Pacific, possibly via a series of connecting rivers, perhaps working in some kind of ladder formation. This would drastically improve the speed it would take to move from coast to coast as you wouldn’t have to slog overland. We now know that the Northwest passage doesn’t exist, but back in 1803, there was still plenty of hope.

If you’re wondering why on earth they needed to go north and then west, it’s because the United States wasn’t the only grand power in the area. The Spanish still controlled vast swaths of what we now consider the continental U.S, including present-day, California, New Mexico, Nevada, Oklahoma and Texas. The Louisiana purchase had essentially created three separate strips of country; the United States, its new territories in the middle and the Spanish to the west. The only section still unclaimed (and largely unexplored) was the northwest, including modern-day Washington, Oregon, Montana and Idaho.      

Lewis and Clark

Lewis and Clark – two names that now sound odd without the other. Like Bonnie and Clyde, Turner and Hooch and, um, Cheech and Chong. The two men who would lead the most famous expedition in US history had been close friends for some time and when President Jefferson formed the Corps of Discovery in 1803 he placed Lewis in charge, with Clark as his deputy.  

Lewis had spent several years in the military where he rose to the rank of Captain before becoming Private Secretary to the President in 1801. Clark too had served in the military and had distinguished himself during the Northwest Indian War, which lasted between 1785 and 1795. However, in poor health, Clark retired when he was just 26 years old to his plantation in Louisville – but seven years later, he was tempted out of retirement by the prospect of a grand adventure.  


While Clark was refused the rank of Captain by Congress which would have placed him as an equal with Lewis, a mutual decision was taken that responsibilities would be shared. But that just left the question of who else would form the group. A multi-year expedition was a tall order even for the hardiest of men. And yes it was all men, except for one very famous Native woman, who I’ll come to later in the video. 

In total, the group was composed of two officers (Lewis and Clark), five non-commissioned officers and thirty privates along with 4 permanent civilians and 12 temporaries, many of whom were boatmen needed for the early stages of the journey. Some were recruited on the east coast, others from the winter staging post in Missouri were the group trained before their departure.  

This group was uniformly male and also white, with one exception. Included in the group was an African-American man by the name of York, who had been Clark’s slave before the expedition. He was often warmly welcomed by local tribes along the way and eventually won his freedom in 1811. 

Now, remember this was the beginning of the 19th Century and despite the lofty ideals set out in the U.S Constitution, it was abundantly clear that, no, not all men were created equal. Slavery still played an enormous role across the country and it would be over 100 years until women were given the vote. Much of this was perfectly legal at the time, but the Corps would be slightly different. It was decided that once the party left U.S territory (the new area seems to have not been included here) it would be entirely egalitarian – meaning each man and woman, regardless of colour, would be given one vote on every activity and decision. 

Camp Dubois reconstruction
Camp Dubois reconstruction by Kbh3rd is licensed under CC-BY-SA

The winter of 1803/1804 was spent at Camp DuBois, north of St. Louis in Missouri. Here Clark recruited the final members of the party and put the group through extensive training to better prepare themselves for the mammoth journey ahead. Lewis on the other hand was busy collecting supplies. These included surveying instruments such as compasses, quadrants, telescope, sextants and a chronometer. Plenty of camping supplies, including oilcloth, steel flints, tools, utensils, corn mill, mosquito netting, fishing equipment, soap and salt. There was, of course, plenty of all-weather clothing, weapons, ammunition, medicines and medical supplies as well as books on botany, geography and astronomy and of course maps. 

They would also be taking plenty of items to be used as gifts to be presented to Native tribes along the way. These included beads, face paint, knives, tobacco, ivory combs, bright-coloured cloth, ribbons, sewing notions and mirrors. But perhaps the most shamelessly showy gifts were the Indian Peace Medals that had been purposely made for the expedition. These were silver and looked similar to an Olympic medal today with an image of Thomas Jefferson emblazoned on one side and a handshake on the other. They were to be distributed to chiefs along the route, no doubt as a symbol of peace, but also a slightly clumsy attempt to appeal to the chief’s ego. It worked on some chiefs, but certainly not on all.   

The Expedition Begins

On 14th May 1804, Clark and the rest of the men set out from Camp DuBois and travelled north on the Missouri River to St Charles where they made their final preparations. Six days later they were joined by Lewis, and for the first time, the group was all together.

The Corps of Discovery formally departed on 21st May 1804, travelling up the Missouri River on a 16.7 metre (55 ft) keelboat through what is now Missouri, Kansas and Nebraska. With the strong currents, the going was slow and just three months into the journey the group suffered their only death when Sergeant Charles Floyd died of acute appendicitis on 20th August 1804. He was buried at a spot that would later become Sioux City in Iowa and the group named a small river nearby after him. 

As their route moved north they began encountering more and more local tribes. Throughout their journey, they would encounter roughly 50 separate groups, with varying degrees of friendliness and hostility. The Corps quickly established a first contact protocol that they tried to mimic with each new encounter. This began with the bartering of goods and the presentation of a peace medal to the local chief. This was followed by the slightly awkward conversation involving the news that their land was now owned by the United States, but that they would be granted military protection in exchange for peace. 

This seemed to work well in the early stages but there were continuous murmurings of war-like tribes further north who wouldn’t be as accommodating. As they entered what is now South Dakota, they encountered the Lakota Sioux for the first time. The Sioux were by the least friendly tribe they had met so far and initially blocked the river to prevent the group from moving past. The two sides met on several occasions and it seemed that a conflict might be inevitable, but the Sioux eventually relented and the explorers passed without incident. 

Winter at Fort Mandan  

Fort Mandan
Fort Mandan by Gooseterrain2 is licensed under CC-BY-SA

As the temperature began to fall, Lewis and Clark knew they had to find an appropriate place to spend the winter. An assault on the perilous Rocky Mountains during the coldest months of the year would have been nothing short of suicidal. 

The spot that was chosen lay on the banks of the Missouri River around 19 km (12 miles) from present-day Washburn in North Dakota. The group began constructing a small fort on 2nd November 1804, which was soon christened Fort Mandan, after a friendly local tribe. Triangular in shape, the fort was built using cottonwood lumber and included storage rooms and a small living space for the men. 

Throughout the winter, Lewis, in particular, worked on improving relations with the local tribes. Numerous native Americans even spent the night at Fort Mandan, but it is also here that we see a slight shift from blanket diplomacy with every tribe to more of a tactical alliance approach. Both Lewis and Clark had begun to realise that expecting a warm welcome from every tribe they came across was unrealistic and set about improving and cementing relationships in the hope of striking some kind of accord. Even at this early stage, the idea of dividing and conquering was already underway.  

It was also here that one of the most famous characters of the entire Lewis and Clark tale appears. The expedition needed a new guide and by chance, they were introduced to Toussaint Charbonneau, a French-Canadian explorer who came with two native wives he had likely either won or bought; Otter Woman and a young 16 year old by the name of Sacagawea. This young woman would go on to play a vital role in the expedition and her name has quite rightly been immortalized in American history. So much so that there are more statues of Sacagawea than any other woman in the US today. And there was one more, rather small addition to the group over the winter. On 11th February 1805, Sacagawea gave birth to a son, Jean Baptiste Charbonneau, who would accompany the Corps every step of their journey.  


The group had survived the winter and began pushing onwards on 6th April 1805, continuing along the Missouri River. When it became too narrow for their keelboat, they sent it and some of the crew back down the river along with some of the plant and animal specimens they’d found. The rest of the group headed west in canoes and eventually crossed the formidable Continental Divide at the 2,247 m(7,373 feet ) Lemhi Pass – they were now entering a land that they believed no white man had ever seen. 

The canoes quickly became of no use and with Sacagawea’s help the group was able to purchase horses from the local Shoshone tribe, the very tribe Sacagawea had been kidnapped from four years before. If there was any doubt of her continuing with the group it’s never mentioned, and her presence has been credited with easing hostilities with tribes along the entire route. In many ways, the young girl with a newborn infant strapped to her back became one of the most important members of the whole group. 

With the aid of the horses, the group set out on what we today know as the Lolo Trail. This is generally considered to have been the most difficult stretch of the entire journey, with many of the party suffering from frostbite, hunger, dehydration, and exhaustion, further compounded by bad weather and freezing temperatures. After 11 hellish days, the groups stumbled deliriously into the area of a local tribe known as the Nez Perce. Had this tribe been hostile, it may have signalled the end of the entire expedition, but the Nez Perce graciously took in these weary, skinny white ghosts. 

Here they built canoes and left the horses in the care of the Nez Perce before continuing down the Snake River and then the Columbia River. On 7th November 1805, the group glimpsed the twinkling of the Pacific Ocean for the first time, but it would take another two weeks before they finally arrived. 

Winter at Fort Clatsop   

No doubt as the group prepared for their second winter there was a euphoric sense of completion. They had after all reached their goal of the Pacific Ocean but another winter and the long return journey lay in store. 

Fort Clatsop
Fort Clatsop by Kingofthedead is licensed under CC-BY-SA

Construction of Fort Clatsop began on 10th December 1805 and the group was inside by the 24th December, but this would prove to be a much harsher winter than before. The cold and damp made it difficult to keep warm and dry and everybody in the group suffered from stomach problems, hunger or flu-like symptoms.

The Return

It had taken them the best part of 18 months to reach the Pacific Ocean but now they faced the prospect of the long return journey. In theory, it would be much faster as the route had already been set out, and so it was, but not without its fair share of drama. 

After crossing the Continental Divide the group split into two to gain a better understanding of the terrain around them. Shortly after, the group led by Lewis encountered the local Blackfeet Tribe. During the night, members of the tribe attempted to steal guns from the party. A fight broke out and two of the Blackfeet tribe were killed. Lewis and his men fled the scene and covered a reported 160 kilometres (100 miles) before they were sure they were far enough away. Remarkably, these were the only two deaths caused by the Lewis and Clark Expedition. 

If things were getting a little rocky, they were exacerbated by one of their men accidentally shooting Lewis in the thigh, believing him to be an animal (it’s since been said that the man wasn’t exactly blessed with the greatest of eye sights). 

The two groups reunited in August 1805 and were able to make their way down the Missouri River at a rapid pace and reached St. Louis on 23rd September 1806. In a little less than 2 and a half years, the expedition had covered roughly 12,874 km (8,000 miles).  

After the Expedition       

The expedition returned to the glowing adulation it deserved. It was seen as a triumph, albeit one slightly tempered by the news that the northwest passage certainly didn’t exist. The knock-on effects of the mammoth exploratory journey were complex and varied. Trade blossomed and the young United States was able to thrive thanks to the huge increase in land and resources.

The expedition would go on to embody the idea of manifest destiny – a belief that it was the American right and destiny to populate everything from sea to shining sea. And we all know what came next. On the whole, the actions of the party towards the local tribes were more than reasonable, but in the coming years, those who followed wouldn’t be as forthcoming. Statistics around this point are complicated, but it’s thought that as much as 90% of the native American population was wiped after the arrival of the Europeans and the spread of the Americans across the continent – accounting for perhaps as many as 20 million people. The Lewis and Clark Expedition may have fostered friendly relations with many tribes, but what came next for most of those tribes was nothing short of tragic. 

As for the characters, well, it’s not that cheerful there either. Both Lewis and Clark were rewarded handsomely for their troubles. Clark was given a series of important roles relating to Indian affairs, before becoming governor of the Missouri Territory. Lewis, on the other hand, suffered misfortunes from the get-go. He endured financial problems and quickly fell into debt, which was made worse by his decline into alcoholism. On 11th October 1809, while on route to Washington to attempt to address his financial problems, he killed himself with a single gunshot to the head. 

Sacagawea died at the age of just 25 of unknown causes, but her young son and a daughter she had given birth to after the expedition, had already been entrusted to Clark who offered to pay for their education.  

And on that rather sad note, we come to the end of the story of the Lewis and Clark Expedition. A mammoth undertaking that explored new lands and opened up countless new possibilities for the United States. But it was also a journey that signalled the beginning of the end for many of those they met along the way. For better or worse, it was a journey that changed the United States of America forever.   

Lewis and Clark Expedition – Wikipedia

Lewis and Clark – Expedition, Trail & Timeline – HISTORY

– The Washington Post

Lewis and Clark . Inside the Corps . The Corps | PBS

Home | Discovering Lewis & Clark ® (lewis-clark.org)

Lewis and Clark Trail | National Geographic Society

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