The Smithsonian Institution was founded for the "increase and diffusion" of knowledge from a bequest to the United States by the British scientist James Smithson (1765–1829), who never visited the new nation. In Smithson's will, he stated that should his nephew, Henry James Hungerford, die without heirs, the Smithson estate would go to the government of the United States for creating an "Establishment for the increase & diffusion of Knowledge among men". After the nephew died without heirs in 1835, President Andrew Jackson informed Congress of the bequest, which amounted to 104,960 gold sovereigns, or US$500,000 ($10,100,997 in 2008 U.S. dollars after inflation). The money was invested in shaky state bonds, which quickly defaulted. After heated debate in Congress, former President John Quincy Adams successfully argued to restore the lost funds with interest.[2] Congress also debated whether the federal government had the authority to accept the gift. Congress accepted the legacy bequeathed to the nation and pledged the faith of the United States to the charitable trust on July 1, 1836.[3] Many of the Institution's buildings are historical and architectural landmarks. When the Detroit philanthropist Charles Lang Freer donated his private collection to the Smithsonian and funds to build the museum to hold it (which was named the Freer Gallery), it was among the Smithsonian's first major donations from a private individual.

Though the Smithsonian's first Secretary, Joseph Henry, wanted the Institution to be a center for scientific research, before long it also became the depository for various Washington and U.S. government collections. The United States Exploring Expedition by the U.S. Navy circumnavigated the globe between 1838 and 1842. The voyage amassed thousands of animal specimens, an herbarium of 50,000 samples, shells and minerals, tropical birds, jars of seawater, and ethnographic artifacts from the South Pacific. These specimens and artifacts became part of the Smithsonian collections, as did those collected by several military and civilian surveys of the American West, including the Mexican Boundary Survey and Pacific Railroad Surveys, which assembled many Native American artifacts and natural history specimens.