Lewis and Clark Expedition: America Explores Its New Territory

The Louisiana Purchase Treaty, signed with France on April 30, 1803, doubled the size of the United States. This vast area, stretching from the Gulf of Mexico to Canada, and from the Mississippi River to the Rocky Mountains, contained unknown territory that President Thomas Jefferson was eager to explore. He convinced Congress to appropriate $2,500 to mount an expedition, and chose Captain Meriwether Lewis to lead it.

To help lead the expedition, which later was named the Corps of Discovery, Lewis chose “Captain” William Clark (who technically was a Second Lieutenant). Preparations began in 1803, including travel to the winter staging area of Camp Dubois in Illinois Territory, and the expedition officially began exploring the Louisiana Purchase lands on May 14, 1804. For more than two years they traveled thousands of miles, their expedition ending with their return to St. Louis on September 23, 1806.

Article continues after this newspaper image from the July 24, 1805, issue of the Democrat (Boston, Massachusetts)

The Lewis and Clark expedition was the first American overland trip to the Pacific Ocean and back. They mainly followed the Missouri River during their journey. The goal of the expedition was scientific; its primary purpose was gathering information on the geography and topography they encountered, as well as compiling a record of the numerous Indian tribes in the vast area, and the various species of plants and animals.

As the authorizing resolution of the House Committee of Commerce and Manufactures stated: “It is highly desirable that this extensive region should be visited, in some parts at least, by intelligent men. Important additions might thereby be made to the science of geography. Various materials might thence be derived to augment our knowledge of natural history. The government would thence acquire correct information of the situation, extent and worth of its own dominions, and individuals of research and curiosity would receive ample gratification as to the works of art and productions of nature which exists in those boundless tracts.”

The expedition achieved its scientific goals, and produced the first solid, reliable maps of the area. Furthermore, it strengthened the U.S. claim on the Oregon Territory (the British claimed it as their own), and helped establish relations with western Indian tribes.