Lewis and Clark’s Corps of Discovery

US #1063 was issued for the 150th anniversary of the expedition. Click image to order.

On May 21, 1804, Lewis and Clark’s Corps of Discovery departed St. Charles on the Missouri River to begin their exploration of the American West.

In 1803, Robert Livingston and James Monroe struck “the greatest real estate deal in history” – the Louisiana Purchase.  As representatives for President Thomas Jefferson, they purchased a 530-million-acre area for $15 million, or about 3¢ per acre.

The 1803 Louisiana Purchase sparked interest in westward expansion.  However, little was known about the territory.  Shortly after the purchase, President Jefferson convinced Congress to appropriate $2,500 to fund an expedition led by Captain Meriwether Lewis and William Clark.  The purpose of the expedition was to find a direct and predictable waterway across the continent for commerce.  In addition, the group was to study Indian tribes, botany, and geology in the territory.

 #3856b – Lewis & Clark pane of 10. Click image to order.

By many accounts, the expedition began on May 14, 1804.  On that day, Clark and a group of men in three boats departed Camp River Dubois, Illinois.  They traveled to St. Charles, where they would wait several days for Captain Lewis, who had business to attend to in St. Louis.  Then on May 20, Lewis rode over land to St. Charles to meet up with Clark and the rest of the Corps.  They would begin their journey together the next day.

US #3854 pictures Lewis and Clark on a hill surveying the countryside. Click image to order.

The Corps of Discovery, led by Lewis and Clark, officially set out about 3:30 p.m. on May 21, 1804.  The men on the boats, as well as those watching from the shore, cheered as the expedition left for its long journey.  Officially, Lewis and Clark were assigned to find a path to the Pacific Ocean, preferably by water, in order to build trade.  But for Jefferson, who was very interested in all natural sciences, it promised to be a treasure trove of knowledge, as well.

By late 1804, the expedition reached Fort Mandan in central North Dakota, where they set up their winter camp.  While there, Lewis and Clark sent a shipment to Jefferson of some of their findings.  Four boxes, two trunks, and three cages were shipped to Washington, D.C.  They included Native American items, as well as animal skins, bones, and antlers.  They also sent a live prairie dog, four magpies, and a grouse.  In addition, Jefferson received plant, soil, and mineral samples.

Item #BK297 – 32-page Lewis & Clark Prestige booklet. Includes 20 stamps, facts, and maps that take you on their journey! Click image to order.

A delighted Jefferson cataloged the contents and then shipped them to at least three different locations, including Monticello, the American Philosophical Society in Philadelphia, and the Peale Museum in Baltimore.  In all, 108 plant and animal specimens, 68 mineral samples, and William Clark’s map were received.

US #3854-56 – 2004 Lewis and Clark First Day Cover. Click image to order.

Meanwhile, out west, a young Shoshone woman named Sacajawea joined the group and guided them westward in the spring.  Sacajawea served as a translator during the journey.  In addition to her interpretations, the sight of a woman with an infant helped divert hostile actions by other Indian tribes.

US #UX91 – Lewis and Clark Silk Cachet First Day Postal Card. Click image to order.

Then in December of 1805, Lewis and Clark traveled down the Columbia River to reach the Pacific Ocean.  Clark wrote in his journal, “Ocean in view! O! The Joy!” They then spent the winter camped in Oregon before beginning their journey home.  The expedition returned to St. Louis on September 23, 1806.  Over the course of 28 months, they traveled 8,000 miles.  In spite of the grueling journey through unknown territory, the only expedition death resulted from appendicitis.

Item #571475 – Commemorative cover marking Lewis & Clark’s return to St. Louis.  Click image to order.

The Lewis and Clark expedition discovered vital information about America’s new territory and the native tribes who inhabited the land.  Lewis and Clark described 178 plants and 122 species of animals as they traveled along the Missouri, across the Continental Divide, and to the Pacific Ocean.  Carefully documented information gathered by the group members resulted in the first accurate mapping of the United States west of the Mississippi River.

Click here for more stamps and covers honoring the expedition.

Click here to read daily journal entries from Lewis, Clark, and others involved in the expedition.

Click here to see what else happened on This Day in History.

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  2. Great article Mystic. You have got me questioning how they were able to have Sacajawea with her infant join their expedition. I will have to do some research. However it came to be it was brilliant that it diverted hostile actions.

    1. She was an extraordinary woman, really a teenager at the time. I encourage you to do the research regarding her part in the expedition.

  3. How Brave and Skilled ( and smart to have that Air Rifle with them)
    that group were. They and Jefferson should never be forgotten.

  4. The expedition actually reached the Pacific Ocean in November of 1805. One little but interesting factoid: When Clark wrote, “Ocian (sic.) in view! O! the joy!” he wasn’t actually viewing the Pacific Ocean. It was the Columbia River estuary with the ocean still several miles further west. The men were wet and miserable from the nearly constant rain, but Clark later wrote, “Great joy in camp. We are in view of the Ocian (sic.), this great Pacific Octean (sic.) which we have been so long anxious to see.” Clark was a notoriously bad speller.

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