Across Montana lies the pathway of Lewis and Clark, whose 1804-1806 expedition set out to investigate the people and resources of the newly acquired Louisiana Purchase and seek a navigable passage across the Rocky Mountains to the Pacific. Like earlier French and Spanish voyages across North America, the Corps of Discovery returned with information that would change life in this land forever. In a 19th-century North America marked by turmoil, with Indian nations recovering from five waves of smallpox and pushing west as Europeans raced to conquer more territory, Lewis and Clark differed from earlier explorers, traders, and trappers in the Northern Plains by coming for military, scientific, and economic development reasons. Their expedition shaped agendas and relationships that people of the West are still sorting out between different cultures and between people and the land. The Corps of Discovery included Indians, French, Euro-Americans, men of mixed European and Indian decent, one black, a woman, and a baby, and Indian people of many nations fed, guided, and helped the Corps with few violent altercations. In what is now Montana, the expedition explored 1,900 miles of wilderness, catalogued 63 species of plants and animals new to science, and charted significant geographic features, including sites now recognized as Pompeys Pillar, the Great Falls Portage, the Three Forks of the Missouri, Lemhi Pass, Lolo Pass, Traveller's Rest, and the Upper Missouri Breaks. Montana remains a land of many cultures, and there are still places where the landscape, wildlife, and native plants appear much as the Corps recorded them in their journals, alongside evidence of the cultural cooperation, conflicts, and collisions in values that have defined the West for two centuries.