It may not have been Constitutional, but it was one of the greatest land deals in history and doubled the size of the young United States.
Even before Louisiana was offered for sale, Jefferson was planning a expedition to explore the American West and find a direct trade route to Asia.
President Jefferson's choice to lead an expedition was Captain Meriwether Lewis, his former secretary. In the spring of 1803, Lewis traveled to Philadelphia to buy equipment and to build on his military training by studying with the leading scientists of the day.
A look at the Lewis and Clark Expedition's journey from its departure up the Mississippi in 1804 to its arrival on the Pacific coast of Oregon.
In the aftermath of the Expedition, Lewis and Clark took on new duties and worked to publish the journals and scientific data that Jefferson hoped to share with the wider world.
With the arrival of Native American objects and natural specimens sent back by Lewis and Clark, Jefferson created an "Indian Hall" in Monticello's entrance along with maps of the world and European paintings and sculptures.