May 14, 1804: One year after the United States doubled its
territory with the Louisiana Purchase, the Lewis and Clark
expedition left St. Louis, Missouri, on a mission to explore
the Northwest from the Mississippi River to the Pacific
Ocean.

Even before the U.S. government concluded purchase
negotiations with France, President Thomas Jefferson
commissioned his private secretary Meriwether Lewis
and William Clark to lead an expedition into what is now
the U.S. Northwest.