Major Funding The Laura Moore Cunningham Foundation

Science of Lewis & Clark: Facts

The Expedition

Meriwether Lewis
Short biographies of William Clark and Meriwether Lewis.

In June 1803 President Thomas Jefferson instructed Captain Meriwether Lewis to:

  • Map a new route to the Pacific Ocean
  • Make contact with the Native Americans
  • Obtain specimens for further study
  • Keep a full record of activities during the expedition

That summer, Lewis recruited William Clark to join the expedition. They spent the next year gathering men and supplies. Read Jefferson's instructions to Meriwether Lewis.

At that time very little was known about the uncharted West. Even though they didn't find a water route that went all the way to the Pacific Ocean, their 2,000 mile journey uncovered the Rocky Mountains, many Indian tribes, and about 300 species of plants and animals unknown to science. They described the geology and geography along their route, collected and took notes and made drawings of minerals and gems, and made extensive meteorological (weather) and astronomical (stars, planets, space) observations.

What Lewis and Clark found was surprising, and today their expedition is an important landmark in the history of the United States. With the maps they made and the knowledge of native peoples and science they brought back with them, they made it possible for Americans and other European immigrants to move into and settle a vast territory.


Follow the Interactive Trail Map (from PBS) as Lewis and Clark mapped the west from St Louis to the Pacific Ocean.

Or take a look at a large map of their route. The map was copied from William Clark's original drawing, and appeared in Lewis and Clark's History Of The Expedition published in 1814.

You can read their actual journals online or take a look at facts about their mission.

The Science of the Expedition

Meriwether Lewis

The history books are filled with stories of brave explorers roaming uncharted lands. What made the Corps of Discovery expedition special was its order from President Jefferson to do basic scientific research along the way. Lewis and Clark had to do more than be on the lookout for danger — they had to keep their eyes open for new plants, animals, peoples, and places and keep a record of what they saw.

Meriwether Lewis had to go “back to school” to prepare for his assignment. Jefferson sent Lewis to The University of Pennsylvania in Philadelphia to learn how to scientifically describe specimens, how to preserve plants, how to skin animals, and how to navigate. He had great powers of observation and the ability to convey what he saw in writing.

William Clark

During his military career, William Clark became expert in astronomy and cartography — the study and making of maps. He was responsible for most of the expedition's record-keeping and map-making. He also managed the expedition's supplies and led hunting expeditions for game.

In all their work you'll notice that they focused on details such as “How fast is the river's current” or “What kinds of rocks are these?” Lewis and Clark were great scientific observers and researchers. Be sure to check out these links to their Journals.



Geography and Culture

Lewis and Clark traveled through lands no Europeans had seen before. So they created much more detailed and accurate maps showing the rivers, mountain ranges, and other new features they had discovered. See this Smithsonian site on Mapping the West. And check out this site on The Geography of the Lewis & Clark Expedition.

One of the prominent features they noted as they paddled down the Snake and Columbia rivers were the mighty Cascade volcanoes. The U.S. Geological Survey has a site devoted to the Lewis and Clark volcanoes.

Expedition members encountered many Native American tribes during their journey. And without the assistance of Indian people, the expedition would not have succeeded. Learn about some of the major tribes. Lewis and Clark wintered with the Nez Perce in Idaho. Learn what some of their descendents have to say.


The Expedition Trail crosses rivers, canyons, ranges, forests, plains, plateaus, and the Continental Divide. It covered (then and now) some of the largest undisturbed tracts of sagebrush steppe habitat. These terrestrial (land) and aquatic (water) habitats support a large variety of wildlife and plant species. The Nez Perce National Historic Trail still has some high quality native habitat just like it was back then. Take a look at the plants and animals along the Nez Perce National Historic Trail.


Lewis and Clark found 122 animals then unknown to science. View a list of the animal life along the Lewis and Clark Trail. Read about the explorers' experiences with animals along the journey. Some people thought that Lewis and Clark might find prehistoric creatures like wooly mammoths on their journey. Do you think they found them?

Learn about some of specific animal species the Expedition discovered.


They also discovered 178 plant species previously unknown to science. Read about some of plant life along the Lewis and Clark Trail.

Learn about some of specific plant species the Expedition discovered.

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