This beautifully illustrated picture book tells the incredible true story of Meriwether Lewis and William Clark's daring expedition across America. In 1804, President Thomas Jefferson sent the Corps of Discovery to explore the newly purchased Louisiana Territory, map a route to the Pacific Ocean, and document the land's plants, animals, and Native American tribes. Through vivid artwork and clear text, readers follow their two-year journey of discovery, hardship, and cooperation, guided by the invaluable help of Sacagawea, a Shoshone interpreter.