The Corps of Discovery: Definition, Timeline & Members

Instructor: Christopher Prokes

Chris is an instructional designer and college faculty member. He has a Master's Degree in Education and also umpires baseball.

The Corps of Discovery were the first Americans to explore new lands purchased for the U.S. and its people. Learn about this important group's formation, membership, and key dates of their trip in this lesson.


Today, we seem to take for granted how fast we can travel from coast to coast across the United States. A flight might take a few hours, and driving only takes a few days. But 200 years ago, when the interior of the nation was a recent purchase (literally), there was a need to explore and discover these native lands. And in that case, travel took months (if not years!), and no return was guaranteed.


In 1803, the United States government bought nearly one million square miles of land west of the Mississippi River from France for $15,000,000. This was called the Louisiana Purchase. Given the fact that this purchase doubled the size of the United States, that is one heck of a deal! Think of upgrading from one home to another as a child; you probably got a bigger room and you didn't even have to pay for it! (though your parents would roll their eyes at that statement). The Louisiana Purchase was just like getting that bigger room. Basically, the U.S. had more places to stretch its legs and store its toys.

Of course, no one had seen the land yet. What was the terrain like? Who--if anyone--lived there and what were their customs? What animals and plants would be found? Would there be danger? These questions needed answers. So Thomas Jefferson, then President, ordered the exploration of these new lands and authorized the creation of an expeditionary group which would come to be known as the Corps of Discovery.

The Louisiana Purchase
Louisiana Purchase Map

To lead this motley crew, Jefferson appointed his secretary Meriwether Lewis, who then recruited his friend, William Clark, to join him. Clark volunteered without knowing what he was in for, and did so since his friend was going to be on the voyage as well. You can imagine his parents now when they asked him, 'If Meriwether jumped off a cliff, would you jump too?'

These two would become known throughout American history as great explorers, but they recruited more than 30 more men to join them. These additional members were primarily soldiers of varying ranks, but they brought with them a large skill set including hunting, trapping, and translating. Civilian personnel were also included, and all the people in the Corps were paid modestly for their services. Think of it as an allowance for doing chores, because most of what the members did was take care of the basic needs of the group. With the Corps of Discovery recruited, supplies were gathered and maps were drawn. The group set out from St. Louis, Missouri on May 14, 1804.

(L-R) Meriwether Lewis, William Clark, & Thomas Jefferson
Lewis, Clark, Jefferson

Timeline of the Expedition

1801 - Thomas Jefferson elected President of the United States.

April 30, 1803 - Louisiana Purchase is made between France and United States. The land is west of the Mississippi River to the Pacific Coast.

Summer 1803 - Meriwether Lewis, already in charge of the trip, adds William Clark to his team as co-leader, and begins to recruit others.

May 14, 1804 - Corps of Discovery sets out from St. Louis, Missouri up the Missouri River.

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