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Did the Lewis and Clark Expedition Have an Ulterior Motive?

Last Modified Date: February 05, 2024

Not long after the Louisiana Purchase in 1803, President Thomas Jefferson dispatched Meriwether Lewis and William Clark to explore and map the newly acquired western territory and establish trade ties with the Native Americans living there. Another goal of the three-year expedition was to study the area’s plant and animal life. There was one creature in particular that Jefferson desperately hoped to find in these new, uncharted lands: the mastodon.

For much of his life, Thomas Jefferson had been fascinated by bones and fossils and obsessed with American mastodons. He was convinced that these tree-chewing beasts were still out in the world somewhere, tearing up the wilderness with their tusks. Sadly for America's most famous paleontologist-president, the mastodon disappeared around 10,500 years ago, mostly likely as a result of hunting pressure from prehistoric humans.

Thomas Jefferson and 18th-century paleontology:

In Jefferson's time, the concept of extinction was considered a violation of both religious and secular ideals. That thinking began to change as the 19th century progressed.

Several years before the Lewis and Clark Expedition, Jefferson famously obtained prehistoric bones that were found in a cave in 1797. The bones turned out to be a nine-foot (2.7-m) giant sloth that lived thousands of years ago, now dubbed Megalonyx jeffersonii.

In his book Big Bone Lick: The Cradle of American Paleontology, author Stanley Hedeen describes Jefferson’s fascination with the fossils being found in North America, particularly the large number unearthed at Big Bone Lick in Kentucky. Jefferson even sent William Clark on an expedition to Big Bone Lick in 1807, from which Clark sent back 300 fossils to the White House.