Sacagawea was a Shoshone Native American who was captured by another tribe at age 12 and sold to a French trapper. In 1804, at age 16, she joined the Lewis and Clark Expedition as a guide and interpreter to help them explore the Western United States and reach the Pacific Ocean. The expedition was commissioned by President Thomas Jefferson to survey the newly acquired lands west of the Mississippi River and find a water route to the Pacific. Sacagawea proved invaluable in helping Lewis and Clark navigate through the rough terrain and communicate with other Native American tribes.