In 1846 America, a young, vibrant republic, was expanding in directions unimagined only a few years earlier. The nation plunged into war with Mexico and rushed to settle the West. The country saw the steady rise of cities, the expansion of the railroad, and the emergence of great works of literature and art.

On August 10 of that year, in an act that embodied the country's buoyant mood, Congress accepted the bequest of Englishman James Smithson and established an institution dedicated to the "increase and diffusion of knowledge.".

Marking the Smithsonian Institution's 150th anniversary, 1846 evokes the texture of American daily life, thought, and politics during a single influential year. In a narrative accompanied by nearly two hundred illustrations, Margaret Christman revisits a capital dominated by Daniel Webster, John C. Calhoun, and James K. Polk and follows the westward journeys of Brigham Young, Francis Parkman, and the ill-fated Donner party.

Moving from the Transcendentalists to the Hudson River School, from Gothic Revival architecture to anesthesia and the sewing machine, Christman chronicles as well the antislavery movement and other social-reform campaigns that expanded the nation's conscience and changed its future.