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 to 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 changed life in this land. In the 19th century, as Indian nations recovered from five waves of smallpox and pushed west while Europeans raced to conquer more territories, Lewis and Clark were the first to enter the Northern Plains for military, scientific, and economic development purposes. Their expedition shaped agendas and relationships in the West that continue to affect relations between cultures and between people and the land. The Corps of Discovery included Indians, French, Euro-Americans, men of mixed European and Indian descent, one black man, a woman, and a baby, and Indian people of many nations fed, guided, and helped the party 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 seven National Historic Landmarks and Monuments: 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, where the landscape, wildlife, native plants, cultural cooperation, conflicts, and collisions in values reflect a legacy that has defined the West for two centuries.