​In 1803, President Thomas Jefferson set in motion one of the most legendary expeditions in American history. He envisioned a journey to explore the newly acquired western territories and determine whether an overland route to the Pacific Ocean was feasible. His plan centered on two major rivers—the Missouri and the Columbia—which he hoped would provide an efficient transportation route for American traders.

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Funding and the Louisiana Purchase

On February 28, 1803, Congress approved funding for a small U.S. Army expedition. Its mission was to chart the Missouri and Columbia Rivers, establish trade relations with Native American tribes, and document the geography, climate, flora, and fauna of the West. Just as preparations were nearly complete, the U.S. acquired the vast Louisiana Territory from France, doubling the nation's size and ensuring that the expedition could travel westward on American soil without requiring foreign permissions.
 

Leadership: Lewis and Clark

To lead the expedition, Jefferson appointed Meriwether Lewis, a 28-year-old Army captain from Virginia. Lewis, an expert outdoorsman, had an extensive knowledge of native plants and animals. He had also served as Jefferson’s private secretary. To co-lead, Lewis selected his former military comrade, 32-year-old William Clark, a skilled frontiersman and the younger brother of Revolutionary War hero George Rogers Clark.
 

Preparing for the Expedition

Lewis received training in astronomy, navigation, and field medicine from scientific experts in Philadelphia. He was also instructed to gather intelligence on Native American customs and languages. Before departing, he purchased a Newfoundland dog named Seaman, who would accompany the expedition.

In December 1803, Lewis and Clark established their staging point near St. Louis, Missouri, where they recruited skilled woodsmen and military personnel. By spring, a team of about 45 men was selected, and on May 14, 1804, the Corps of Discovery embarked on their historic journey.
 

Facing Challenges on the Lower Missouri 

Traveling in a 55-foot keelboat and two smaller pirogues, the team navigated the treacherous Missouri River. They encountered strong currents, submerged trees, and sudden storms. Discipline was strict—floggings were administered for misconduct, and two men deserted. The only fatality occurred when Sergeant Charles Floyd succumbed to an apparent case of appendicitis. In present-day South Dakota, a tense standoff with the Teton Sioux nearly turned violent, but the explorers’ superior weaponry allowed them to continue without bloodshed.
 

Winter at Fort Mandan and the Arrival of Sacagawea

By November, the expedition reached the villages of the Mandan and Hidatsa tribes (in present-day North Dakota). There, they built Fort Mandan and spent the winter trading with Indigenous peoples and gathering intelligence about the lands ahead.

It was here that they met Toussaint Charbonneau, a French-Canadian trader, and his young Shoshone wife, Sacagawea. Since Sacagawea spoke both Shoshone and Minitari, she would serve as an invaluable interpreter when negotiating for horses to cross the Rocky Mountains. She, Charbonneau, and their newborn son, Jean Baptiste, joined the expedition in the spring of 1805.
 

Navigating the Upper Missouri and the Rocky Mountains (April - November 1805)

As the team continued westward, they encountered vast herds of buffalo and aggressive grizzly bears. In May, they reached the confluence of the Missouri and Yellowstone Rivers, eventually sighting the Rocky Mountains. Navigation became even more difficult, requiring them to drag and carry their boats over land. At the Great Falls of the Missouri, a grueling 18-mile portage took nearly a month.

In August, Lewis crossed the Continental Divide at Lemhi Pass and encountered the Shoshone people. In an emotional reunion, Sacagawea discovered that their leader, Cameahwait, was her long-lost brother. The Shoshone provided much-needed horses, and the expedition set out on the arduous journey across the Bitterroot Mountains. Starving and exhausted, they eventually reached the friendly Nez Perce tribe, who provided food and assistance.
 

Reaching the Pacific (November 1805 - March 1806)

After constructing new canoes, the team followed the Clearwater, Snake, and Columbia Rivers. In early November, they finally reached the Pacific Ocean. Clark recorded in his journal: 📝 "Great joy in camp we are in view of the ocean." Mistakenly, the Corps thought that they could see the Pacific.

That exuberant moment of joy turned to misery when rough water and torrential rain drove them to camp under the bay’s sheer cliffs and kept them stranded for days.
 

Seeking shelter, the group voted to move to the south side of the Columbia River. This is one of history’s first recorded democratic votes, where Sacagawea and York, Clark’s enslaved servant, participated in deciding where to camp.

At Fort Clatsop they hunted elk, mapped the territory, and documented local plants, animals, and Native American cultures. 

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The Return Journey (March - September 1806)

On March 23, 1806, the Corps began their return trip. Splitting into two groups, Lewis explored the Marias River while Clark mapped the Yellowstone.
👉During a brief skirmish with Blackfeet warriors, two Native Americans were killed, marking the only violent encounter of the expedition. Lewis left a peace medal around the neck of one of the Natives whom Reuben Fields had killed in self defense beside the Two Medicine River in northwest Montana on July 17, 1806.
👉Meanwhile along the Yellowstone River, Clark named a rock formation “Pompy’s Tower” after Sacagawea’s son.
📝July 25, 1806: "This rock which I shall Call Pompy's Tower is 200 feet high.  The nativs have ingraved on the face of this rock the figures of animals & near which I marked me name and the day of the month & year."

The split-up groups reunited on August 12, and by September 23, 1806, they triumphantly returned to St. Louis.

📝September 23, 1806: "Set out decended to the Mississippi and down that river to St. Louis at which place we arived about 12 oClock. we suffered the party to fire off their pieces as a Salute to the Town. we were met by all the village and received a harty welcome."
 

The Legacy of the Expedition

Over thousands of miles and two years, four months, and nine days, the Lewis and Clark expedition reshaped American knowledge of the West. They mapped uncharted territory, documented hundreds of plant and animal species, and strengthened relations with Native American tribes.

While the sought-after water route to the Pacific did not exist, their findings paved the way for westward expansion.

Their journey remains one of the greatest explorations in history, showcasing resilience, discovery, and the unyielding spirit of adventure.