The Lewis and Clark expedition across the present day United States began May 14, 1804. With the approval of President Jefferson and the U.S. Congress, Lewis and Clark gathered an exploration party of about four dozen men. These men headed off to discover Western America. On September 1, 1805, they arrived at the Bitterroot Mountains, near present day Idaho. This began a nightmare that would not end until they reached modern-day Weippe. September 1, 1805, the explorers set out traveling west, heading into rough, seldom traveled, mountainou ....