Facts about Lewis and Clark found on the National Geographic website include how Thomas Jefferson sent them on an expedition out west in 1803 to find a water route leading to the Pacific Ocean. Thomas Jefferson believed that they would encounter woolly mammoths, volcanoes and a mountain of salt.
The National Geographic website contains a detailed interactive map with a journey log about the expedition of Meriwether Lewis and William Clark, as of July 2015. Lewis and Clark began their journey upstream on the Missouri River in May of 1804. They had been preparing for the journey since the fall of 1803 at their St. Louis-based camp. They began the journey on three boats, a keelboat and two pirogues, and made their way up the Missouri River with a dozen other men.
Clark spent most of his time on the keelboat charting the course and drawing maps, while Lewis spent more time onshore, studying rock formations, soil, plants and animals. They were afraid of meeting unfriendly Indians and would sleep with guards standing watch.
Lewis and Clark's journey lasted until September of 1806 when they finally made it back to St. Louis after having spent two years, four months and 10 days traveling out west and back. Many had already given up on Lewis and Clark, believing them dead.