The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the United States expedition to cross the newly acquired western portion of the country after the Louisiana Purchase. The Corps of Discovery was a select group of U.S. Army and civilian volunteers under the command of Captain Meriwether Lewis and his close friend Second Lieutenant William Clark. Clark and 30 members set out from Camp Dubois, Illinois, on May 14, 1804, met Lewis and ten other members of the group in St. Charles, Missouri, then went up the Missouri River. The expedition crossed the Continental Divide of the Americas near the Lemhi Pass, eventually coming to the Columbia River, and the Pacific Ocean in 1805. The return voyage began on March 23, 1806, at Fort Clatsop, Oregon, and ended on September 23 of the same year.

President Thomas Jefferson commissioned the expedition shortly after the Louisiana Purchase in 1803 to explore and to map the newly acquired territory, to find a practical route across the western half of the continent, and to establish an American presence in this territory before European powers attempted to establish claims in the region. The campaign's secondary objectives were scientific and economic: to study the area's plants, animal life, and geography, and to establish trade with local Native American tribes. The expedition returned to St. Louis to report its findings to Jefferson, with maps, sketches, and journals in hand.

Overview

One of Thomas Jefferson's goals was to find "the most direct and practicable water communication across this continent, for the purposes of commerce." He also placed special importance on declaring US sovereignty over the land occupied by the many different Native American tribes along the Missouri River, and getting an accurate sense of the resources in the recently completed Louisiana Purchase. The expedition made notable contributions to science, but scientific research was not the main goal of the mission.

During the 19th century, references to Lewis and Clark "scarcely appeared" in history books, even during the United States Centennial in 1876, and the expedition was largely forgotten.Lewis and Clark began to gain attention around the start of the 20th century. Both the 1904 Louisiana Purchase Exposition in St. Louis and the 1905 Lewis and Clark Centennial Exposition in Portland, Oregon, showcased them as American pioneers. However, the story remained relatively shallow until mid-century as a celebration of US conquest and personal adventures, but more recently the expedition has been more thoroughly researched.

As of 1984, no US exploration party was more famous, and no American expedition leaders are more recognizable by name.

In 2004, a complete and reliable set of the expedition's journals was compiled by Gary E. Moulton. Circa 2004, the bicentennial of the expedition further elevated popular interest in Lewis and Clark.

Timeline

The timeline covers the primary events associated with the expedition, from January 1803 through January 1807.

The Corps met their objective of reaching the Pacific, mapping and establishing their presence for a legal claim to the land. They established diplomatic relations and trade with at least two dozen indigenous nations. They did not find a continuous waterway to the Pacific Ocean but located a Native American trail that led from the upper end of the Missouri River to the Columbia River which ran to the Pacific Ocean. They gained information about the natural habitat, flora and fauna, bringing back various plant, seed and mineral specimens. They mapped the topography of the land, designating the location of mountain ranges, rivers and the many Native American tribes during the course of their journey. They also learned and recorded much about the language and customs of the Native American tribes they encountered, and brought back many of their artifacts, including bows, clothing and ceremonial robes.