Science of the Expedition

Plant Life|Animal Life

It has been described as "the greatest camping trip of all time," a voyage of high adventure, an exercise in manifest destiny which carried the American flag overland to the Pacific. The Lewis and Clark Expedition was all of this and more. However, it is astounding that the expedition is rarely discussed in terms of its scientific achievements, for the Lewis and Clark Expedition was one of the first systematic scientific evaluations of a region ever conducted.

President Thomas Jefferson soft-pedaled the scientific aspects of the expedition when he asked Congress for money in 1803. The purposes of the expedition were twofold, Jefferson claimed, but only the first purpose was of any real consequence - the diplomatic mission of contacting Indian nations, establishing the United States as sovereign over the region and as a major player in the fur trade. He made the second purpose, the scientific one, seem like an inconsequential afterthought. Jefferson knew that diplomacy, especially with the goal of increased commerce, could be sold to Congress; scientific discovery and description could not. One seemed practical, the other less so.

Yet, as Jefferson wrote letters of introduction for his 29-year-old personal secretary, Meriwether Lewis, to the most distinguished American scientists of the day, he accentuated that second goal. Jefferson told the men of science that Lewis would not only explore but map and chronicle everything of interest. Jefferson was himself an amateur scientist who must stand with the foremost men of his time. Notes on the State of Virginia, his only book, was one of the first examples of Scientific Geography, preceding the work of Humboldt by 50 years, and drawing upon Bernhard Varenius' Geographia generalis (1650). By 1803, Jefferson was probably the most informed American on the totality of the geography of the American West, and had the largest library anywhere on this subject.

Between 1804 and 1806, Lewis and Clark made the first systematic reports, based on scientific measurement and observations, of the Missouri River - not only its course, but its flora and fauna, depth and current, tributaries and inhabitants. They continued onward to document their observations in the Rocky Mountains and the Pacific Northwest. Lewis and Clark described for science at least 120 mammals, birds, reptiles and fish, as well as at least 182 plant species. They made the first attempt at a systematic record of the meteorology of the West, and less successfully attempted to determine the latitude and longitude of significant geographical points.

These facts set them apart from other contemporary expeditions, most notably those of Zebulon Pike, which made no new scientific discoveries. There is a reason that such wonderful, Enlightenment-influenced scientific work was possible on the Voyage of Discovery - and that reason was Meriwether Lewis. If not for Lewis' incredible intelligence, background knowledge of the rudimentary science of his day, powers of observation and his ability to apply this knowledge in the field, the significance of the Lewis and Clark Expedition would be greatly diminished. It was Lewis alone of the expedition members who stood closest to being a man of science, both during and after the expedition. On February 27, 1803, President Jefferson confided in a letter to Benjamin Smith Barton, a physician and naturalist at the University of Pennsylvania, why he chose Lewis to head the expedition, saying that "It was impossible to find a character who to a compleat science in botany, natural history, mineralogy & astronomy, joined the firmness of constitution & character, prudence, habits adopted to the woods, & a familiarity with the Indian manners & character, requisite for this undertaking. . . . Altho' no regular botanist he possesses a remarkable store of accurate observation on all the subjects of the three kingdoms, & will therefore readily single out whatever presents itself new to him in either." Jefferson ended his letter by asking Barton to train Lewis, and continued: "I make no apology for this trouble, because I know that the same wish to promote science which has induced me to bring forward this proposition, will induce you to aid in promoting it." Jefferson wrote similar letters to the other prominent American scientists of the day: Andrew Ellicott, Robert Patterson, Caspar Wistar and Dr. Benjamin Rush. The deaths of Benjamin Franklin and David Rittenhouse left these five men, along with Jefferson, as the leaders of the American Philosophical Society in Philadelphia, the primary scientific society in America at that time.

In 1803 Lewis traveled to Philadelphia to study with Dr. Barton, a professor of botany at the University of Pennsylvania, who instructed Lewis in botany and zoology. Barton was the first professor of natural sciences in the United States and wrote the first U.S. textbook on botany. It is not known whether it was Barton or Jefferson who taught Lewis how to prepare and label plant and animal specimens; either was capable of doing so. Lewis took 10 or 12 natural science reference books with him all the way to the Pacific Ocean and back, including Barton's botany textbook.

Dr. Caspar Wistar rounded out Lewis' instruction in the natural sciences. After teaching chemistry and physiology at the College of Pennsylvania for many years, he was given the chair of anatomy at the University of Pennsylvania's medical school. Wistar published the first U.S. book on anatomy, and was honored by the English-born botanist Thomas Nuttall, who named the vine "Wisteria" after him. Wistar was a specialist at "comparative anatomy." Wistar drew up a list of questions for Lewis involving the natural history of each region of the West. Unfortunately, this original list has never been found.

During the winter spent in the St. Louis area, Lewis and Clark were busy with training their crew, obtaining supplies and finding out all they could about the territory ahead. But the work of scientific inquiry continued, even in the heart of St. Louis, as Lewis sat in the garden of Pierre Chouteau on March 26, 1804. In the stone-walled enclosure, Chouteau had a specimen of the Osage Orange tree growing. The tree's natural range then extended only to about 300 miles West of St. Louis. Chouteau allowed Lewis to take cuttings to send back to Jefferson. Even in the midst of a domestic garden, Lewis noticed an unusual tree and described it for science. This was chronologically the very first of the over 300 plants and animals described by Lewis and Clark over the subsequent 2½ years.

As the expedition began to move up the Missouri River, Lewis focussed on the details - the animals, the type of rocks, the trees and grasses - along the route. How fast was the current? How high the cliffs? Was that bird or plant different from one known in the East? Lewis went on to describe some of the animals, including the eastern wood rat - the first animal new to science encountered on the voyage - in what is today Osage County, Missouri. By this time the tone had been set and the tasks defined for this incredible scientific mission. For, more than a mere stunt to see if the continent could be crossed and conquered, more than a diplomatic mission to Indian peoples, the Lewis and Clark Expedition was a scientific foray. Jefferson charged Lewis with chronicling "the animals of the country generally, & especially those not known in the U.S. the remains and accounts of any which may [be] deemed rare or extinct . . . [observe] the face of the country, it's growth and vegetable productions; especially those not of the U.S. . . ." He was told to make these observations "with great pains & accuracy, to be entered distinctly & intelligibly for others as well as yourself." It is this aspect of the expedition, fulfilled in every sense, which sets the Lewis and Clark Expedition apart and plays a major role in its resonance 200 years later.

Last updated: December 11, 2018

Contact the Park

Mailing Address:

11. North 4th Street
St. Louis, MO 63102


(314) 655-1600

Contact Us