On September 23, 1806, amid great public excitement, the expedition of William Clark and Meriwether Lewis returned to St. Louis, Missouri. They were the first to record an overland journey from the Mississippi River to the Pacific coast and back. Setting out in May 1804, they returned with extensive knowledge of the Louisiana Purchase territory.

In 1803, under President Jefferson, the United States purchased the Louisiana Territory for 3 cents per acre, totaling 828,000 square miles—one of the best land deals in history. Jefferson commissioned Lewis and Clark to explore this territory. The expedition, with about 48 men, traveled up the Missouri River in six canoes and two longboats, wintered in Dakota, and crossed into Montana, where they first saw the Rocky Mountains. They met the Shoshone Indians, who sold them horses, and journeyed through the Bitterroot Mountains, down the Clearwater and Snake rivers, reaching the Columbia River and the Pacific Ocean on November 8, 1805—the first European explorers to do so overland from the east. They wintered there before returning to St. Louis in spring.

Their journals recorded longitude, latitude, soil, climate, animals, plants, and native peoples, identifying new species like the grizzly bear and naming geographic locations after themselves, loved ones, friends, and their dog. Despite diseases and injuries, only one person died. Their expedition, one of the most consequential in U.S. history, helped establish U.S. territorial claims in Oregon.

Sources

Buckley and Jay H, “Lewis and Clark Expedition | Summary, History, Members, Facts, & Map,” Encyclopedia Britannica, last modified July 28, 2025, accessed September 9, 2025, https://www.britannica.com/event/Lewis-and-Clark-Expedition.

“Lewis and Clark Return to St. Louis | September 23, 1806 | HISTORY,” HISTORY, last modified May 28, 2025, accessed September 9, 2025, https://www.history.com/this-day-in-history/september-23/lewis-and-clark-return.

“Louisiana Purchase | Definition, Date, Cost, History, Map, States, Significance, & Facts,” Encyclopedia Britannica, last modified July 29, 2025, accessed September 9, 2025, https://www.britannica.com/event/Louisiana-Purchase.

Under President Jefferson, the United States purchased the Louisiana Territory in 1803 for a price of 3 cents per acre for some 828,000 square miles of land. It is considered one of the best land deals ever. Jefferson commissioned the expedition of Lewis and Clarke to explore this territory  from the Mississippi River to the Pacific Ocean. On 14 May 1804 this “Corps of Discovery” as it was called, left St. Louis with 45 men (only 33 would make the full journey) for the newly purchased American interior.

Traveling up the Missouri River in six canoes and two longboats they would winter in Dakota before crossing into Montana where they saw the Rocky Mountains for the first time. They would meet the Shoshone Indians on the other side of the Continental Divide, who would sell them horses. The journeyed through the Bitterroot Mountains, down the rapids of the Clearwater and Snake rivers, until they reached the Columbia River and to the sea. They arrived at the Pacific Ocean on 8 November 1805 and were the first European explorers to do this overland from the east. The paused for the winter and then made their journey back to St. Louis in the spring.

The journals that were kept noted longitude and latitude with detailed notes on soil, climate, animals, plants, and native peoples. They identified new plants and animals (the grizzly bear for one). They also named geographic locations after themselves, loved ones, friends and even their dog. They experienced a variety of diseases and injuries during their journey but only one person perished. Their expedition is considered one of the most consequential and remarkable in U.S. history. Their travels in Oregon would lead the U.S. to able claim territorial rights later.

Shop for books on Lewis & Clark expedition on Amazon

Sources

Buckley and Jay H, “Lewis and Clark Expedition | Summary, History, Members, Facts, & Map,” Encyclopedia Britannica, last modified April 21, 2025, https://www.britannica.com/event/Lewis-and-Clark-Expedition.

———. “Louisiana Purchase | Definition, Date, Cost, History, Map, States, Significance, & Facts.” Encyclopedia Britannica. Last modified April 25, 2025. https://www.britannica.com/event/Louisiana-Purchase.

HISTORY.com Editors, “Lewis and Clark: Expedition, Purpose & Facts | HISTORY,” HISTORY, last modified May 10, 2025, https://www.history.com/articles/lewis-and-clark.

Under President Jefferson, the United States purchased the Louisiana Territory in 1803 for a price of 3 cents per acre for some 828,000 square miles of land. It is considered one of the best land deals ever. Jefferson commissioned the expedition of Lewis and Clarke to explore this territory  from the Mississippi River to the Pacific Ocean. On 14 May 1804 this “Corps of Discovery” as it was called, left St. Louis with 45 men (only 33 would make the full journey) for the newly purchased American interior.

Traveling up the Missouri River in six canoes and two longboats they would winter in Dakota before crossing into Montana where they saw the Rocky Mountains for the first time. They would meet the Shoshone Indians on the other side of the Continental Divide, who would sell them horses. The journeyed through the Bitterroot Mountains, down the rapids of the Clearwater and Snake rivers, until they reached the Columbia River and to the sea. They arrived at the Pacific Ocean on 8 November 1805 and were the first European explorers to do this overland from the east. The paused for the winter and then made their journey back to St. Louis in the spring.

The journals that were kept noted longitude and latitude with detailed notes on soil, climate, animals, plants, and native peoples. They identified new plants and animals (the grizzly bear for one). They also named geographic locations after themselves, loved ones, friends and even their dog. They experienced a variety of diseases and injuries during their journey but only one person perished. Their expedition is considered one of the most consequential and remarkable in U.S. history. Their travels in Oregon would lead the U.S. to able claim territorial rights later.

Shop for books on Lewis & Clark expedition on Amazon

Sources:

Buckley, Jay H. “Lewis and Clark Expedition | Summary, History, Members, Facts, and Map.” Encyclopedia Britannica, 17 Apr. 2024, www.britannica.com/event/Lewis-and-Clark-Expedition.

—. “Lewis and Clark: Expedition, Purpose and Facts | HISTORY.” HISTORY, 28 Mar. 2023, www.history.com/topics/19th-century/lewis-and-clark.

—. “Louisiana Purchase | Definition, Date, Cost, History, Map, States, Significance, and Facts.” Encyclopedia Britannica, 25 Apr. 2024, www.britannica.com/event/Louisiana-Purchase.

This was first published in 2020. It has been updated in 2024 with new sources.

Under President Jefferson, the United States purchased the Louisiana Territory in 1803 for a price of 3 cents per acre for some 828,000 square miles of land. It is considered one of the best land deals ever. Jefferson commissioned the expedition of Lewis and Clarke to explore this territory  from the Mississippi River to the Pacific Ocean. On 14 May 1804 this “Corps of Discovery” as it was called, left St. Louis with 45 men (only 33 would make the full journey) for the newly purchased American interior.

Traveling up the Missouri River in six canoes and two longboats they would winter in Dakota before crossing into Montana where they saw the Rocky Mountains for the first time. They would meet the Shoshone Indians on the other side of the Continental Divide, who would sell them horses. The journeyed through the Bitterroot Mountains, down the rapids of the Clearwater and Snake rivers, until they reached the Columbia River and to the sea. They arrived at the Pacific Ocean on 8 November 1805 and were the first European explorers to do this overland from the east. The paused for the winter and then made their journey back to St. Louis in the spring.

The journals that were kept noted longitude and latitude with detailed notes on soil, climate, animals, plants, and native peoples. They identified new plants and animals (the grizzly bear for one). They also named geographic locations after themselves, loved ones, friends and even their dog. They experienced a variety of diseases and injuries during their journey but only one person perished. Their expedition is considered one of the most consequential and remarkable in U.S. history. Their travels in Oregon would lead the U.S. to able claim territorial rights later.

Sources:

• Lewis and Clark Expedition (Britannica.com)
• Lewis and Clark Return to St. Louis (History.com)
• Louisiana Purchase (Britannica.com)

Under President Jefferson, the United States purchased the Louisiana Territory in 1803 for a price of 3 cents per acre for some 828,000 square miles of land. It is considered one of the best land deals ever. Jefferson commissioned the expedition of Lewis and Clarke to explore this territory  from the Mississippi River to the Pacific Ocean. On 14 May 1804 this “Corps of Discovery” as it was called, left St. Louis with 45 men (only 33 would make the full journey) for the newly purchased American interior.

Traveling up the Missouri River in six canoes and two longboats they would winter in Dakota before crossing into Montana where they saw the Rocky Mountains for the first time. They would meet the Shoshone Indians on the other side of the Continental Divide, who would sell them horses. The journeyed through the Bitterroot Mountains, down the rapids of the Clearwater and Snake rivers, until they reached the Columbia River and to the sea. They arrived at the Pacific Ocean on 8 November 1805 and were the first European explorers to do this overland from the east. The paused for the winter and then made their journey back to St. Louis in the spring.

The journals that were kept noted longitude and latitude with detailed notes on soil, climate, animals, plants, and native peoples. They identified new plants and animals (the grizzly bear for one). They also named geographic locations after themselves, loved ones, friends and even their dog. They experienced a variety of diseases and injuries during their journey but only one person perished. Their expedition is considered one of the most consequential and remarkable in U.S. history. Their travels in Oregon would lead the U.S. to able claim territorial rights later.

Sources:

• Lewis and Clark Expedition (Britannica.com)
• Lewis and Clark Return to St. Louis (History.com)
• Louisiana Purchase (Britannica.com)