The Lewis and Clark expedition was a two-year, cross-country-and-back-again journey to explore the western territories acquired by the United States in the Louisiana Purchase. The Lewis and Clark expedition made many important discoveries, documenting plants, animals, geographic features, and Indigenous groups it came across along the way. Though the expedition had lofty goals of diplomacy and scientific observation, it later had disastrous consequences.
The United States purchased the Louisiana Territory (extending north into the Canadian province of Alberta and as far west as Montana) at the behest of President Thomas Jefferson in 1803. Jefferson sought an expedient water route across the country, in order to support cross-continental enterprise. He also wanted to inform Indigenous leaders of the transition of power. However, maps of the western United States were lacking, and Jefferson knew little of the areas French settlers had not occupied. An expedition was needed to research the territory and promote diplomacy.
To lead this journey into the unknown, Jefferson selected his childhood neighbor Meriwether Lewis. Lewis, an Army officer, had ample experience in leadership and long-distance travel. However, he had little formal education, so Jefferson sent him to Philadelphia to study astronomy, botany, and medicine.
Lewis asked one of his former commanding officers, William Clark, to be his co-captain. Unlike Lewis, Clark had combat experience, and was a talented cartographer. Although Clark accepted, he was denied a captain’s rank, which he concealed from the rest of the party.
Amid much excitement, the Corps of Discovery set out from Camp Dubois near Hartford, Illinois, on May 14, 1804. Clark and about 30 others shoved off first, crossing the Mississippi River before heading up the Missouri. Lewis remained in St. Louis with another 10 crew members, making last-minute preparations; the two would meet in St. Charles, Missouri. The Corps consisted of soldiers, interpreters, a boat crew, and Clark’s slave York, all aboard the large keelboat and two smaller pirogues.
The Corps had to steer against the river’s current. Although the wind sometimes filled their sails, more often they had to row. Frequent breaks for rest and repair were necessary. Still, they remained in high spirits, barring a handful of desertions, fights, and one death by ruptured appendix. Four days into their journey, they passed La Charette, the westernmost French settlement along the Missouri, entering uncharted territory.
On August 3, 1804, Lewis and Clark had their first meeting with Indigenous leaders of the Otoe and Missouria. Lewis and Clark doled out trade goods and medals bearing Jefferson’s face. These medals signified the transition of power, while recognizing the leaders’ authority over their people.
Like many of these meetings, the first proceeded peacefully. Lewis and Clark would always present trade goods and medals, sometimes participating in ceremonies, asking for directions, or recruiting interpreters. However, they also often made shows of force by demonstrating their weapons.
Not all of these interactions were peaceful. On September 25, 1804, Lewis and Clark encountered Lakota chiefs, including Black Buffalo and Tortohongar. They were accustomed to accepting tolls from travelers. The expedition had no Lakota interpreter, making communication difficult. Lewis initially offered tribute to one chief but not Tortohongar, insulting the latter. He then offered each a share they found insufficient. Warriors commandeered one of the boats, preventing Clark from leaving. The Corps drew their guns, at which point Black Buffalo ordered his warriors to stand down.
In October of 1804, the Corps arrived at a Mandan settlement near present-day Washburn, North Dakota. They were received warmly, and decided to winter there. That winter, they recruited Toussaint Charbonneau, a French trader, and Sacagawea, his pregnant 16-year-old wife.
Sacagawea was born to the Lemhi Shoshone, but taken prisoner in a Hidatsa raid at the age of 12. She was sold to Charbonneau at 13, his second Shoshone wife. She had her son on February 11, 1805, naming him Jean Baptiste, though he was better known by the nickname Pomp. Although she signed on as an interpreter, and served well in that capacity, she had many other skills. She recognized certain landmarks, aiding in navigation. Her knowledge of medicinal plants helped keep the Corps in good health. Sacagawea’s quick thinking also saved Lewis and Clark’s all-important journals when one of the pirogues capsized.
By April 7, 1805, the weather had warmed sufficiently. The return party began its trip back eastward with some of the expedition’s notes and samples, arriving on August 12. The permanent party soon continued into what is now Montana, where they marveled at teeming herds of bison and fended off ferocious grizzly bears.
In western Montana, Sacagawea recognized Beaverhead Rock from her childhood, and the party proceeded to search for her lost people. They encountered a group of Shoshone, who led them back to their settlement. There Sacagawea recognized their chief as her brother, Cameahwait, and they shared a tearful reunion. In gratitude, Cameahwait granted the Corps horses and a guide to aid their passage over the Rocky Mountains.
Lewis and Clark’s passage over the Rockies through Bitterroot Range was the most trying leg of the journey, beset by harsh cold, deep snows, and scant food. However, the entire party survived the harrowing 11 days. They took time to rest and build canoes before continuing.
On November 7, 1805, Clark penned a journal entry in which he claimed to have sighted the Pacific Ocean. In actuality, it was the Columbia River’s estuary, but the sea was only a week’s journey away. However, the last 20 miles were strenuous—storms forced the party ashore, where they buried their boats to prevent them from blowing away. On November 15, 1805, Lewis and Clark reached the Pacific, and constructed a winter camp. Lewis spent the winter writing, while Clark compiled a map.
Success hadn’t come easily, and everyone was anxious to get home. The Corps broke camp on March 23, 1806, but when they returned to Bitterroot Range, the snow hadn’t yet thawed. They waited almost a month among the Nez Perce, who were eventually able to find a more efficient route over the Rockies.
Desiring to chart more terrain, Lewis and Clark planned to split the party in western Montana. On July 3, 1806, Lewis continued down the Missouri River while Clark took the Yellowstone. Clark had a pleasant detour, naming a rock formation Pompeys Pillar, for Sacagawea’s son. Lewis, however, struggled. He and his party clashed with Blackfeet warriors, killing two of them and fearing retaliation. To make matters worse, one of his men accidentally shot him in the rear.
After their reunion near the mouth of Knife River on August 12, 1806, the remainder of the expedition proceeded without incident. Since they were traveling with the Missouri’s current, they were able to cover more ground. On September 23, 1806, the Corps of Discovery arrived in St. Louis, marking an end to their journey.
President Jefferson made Lewis the Governor of Upper Louisiana after his return, but Lewis struggled with debt and alcoholism. He died in 1809 at the age of 35, possibly by suicide. Clark became the Agent for Indian Affairs. Despite attempts to foster peace with Indigenous people, he remained in the position through Andrew Jackson’s presidency, carrying out cruel Indian Removal Act policies.
Sacagawea remained with the Mandan people until 1809, when Clark invited her and her husband to St. Louis. She had a daughter, Lizette, whom Clark adopted along with Pomp; however, Lizette may not have survived childhood. Sacagawea is believed to have died in 1812, although oral traditions claim she escaped Charbonneau and lived to 94.
York was the first Black man to cross the continental United States to the Pacific. Unlike many of his fellows in the Corps, he was able to swim, a skill which proved useful during the expedition’s river travels. He was allowed to wield a rifle, a privilege denied to most slaves. He was the only member of the expedition who received no compensation. After their return, he requested permission to travel to Louisville, where his wife lived. Clark eventually capitulated, expecting him to stay for a few weeks. York stayed until Clark forcibly recalled him months later. Clark whipped him and jailed him, and the two resented each other for the rest of their lives.
Lewis and Clark’s expedition forever changed the face of the country. They blazed a trail that throngs of white settlers would soon follow. Many of the places they visited, like Council Bluffs, Pompeys Pillar, and York’s Island still bear the names Lewis and Clark gave them. They observed and documented 83 species of animals and 55 species of plants, recording their potential economic value. Their reporting on beavers helped the fur trade flourish. Their notes on buffalo drove settlers to hunt them nearly to extinction, eliminating a vital food source for the Indigenous people of the region. Although significant for its scientific discoveries, the Lewis and Clark expedition paved the way for widespread colonization and displacement in the western United States. Their arduous journey has since become a central part of the American national identity.