Thomas Jefferson outlined three motivating factors in his instructions to Lewis and Clark: a search for navigable rivers to span the continent; a quest for Edenic beauty and riches; and the competitive desire to acquire a continental empire. These 180 documents and artifacts interpret 19th-century westward exploration from this perspective. The range of materials is striking. In addition to maps, plans, and charts, the site offers images (sketches, watercolors, etchings, and engravings), texts (letters, diaries, speeches, newspapers, and books), and tools (surveying and medical instruments, cooking utensils, armaments). The exhibit opens with an examination of the "imperial mentality" common to Virginia's aristocratic class in the late 18th century and then focuses on the Lewis and Clark journey. It ends with the subsequent expeditions of Zebulon Pike, Stephen H. Long, Charles Wilkes, John Charles Fremont, and the mid-19th century transcontinental railroad plan that supplanted the search for a water route.

Nearly 4,000 panoramic photographs of cityscapes, landscapes, and group portraits, deposited as copyright submissions by more than 400 companies, are displayed on this site. Panoramic photographs were used to advertise real estate and to document groups, events, and gatherings. Images depict all 50 states, the District of Columbia, and more than 20 foreign countries and territories. Subjects include cityscapes, landscapes, group portraits, agricultural life, disasters, education, engineering, fairs and expositions, industrial scenes, military activities, performing arts, sports, and transportation. Although the images cover the period from 1851 to 1991, the collection centers on the early 20th century. The site includes a bibliography, an illustrated 1,000-word background essay on the history of panoramic photography, and an essay outlining the technicality of shooting a panoramic photograph. Four essays focus on specific photographers: George R. Lawrence (1869–1938); George N. Barnard (1819–1902); Frederick W. Brehm (1871–1950); and Miles F. Weaver (1879–1932).

These varied collections document the history of Los Angeles and southern California. "Digital Archives" offer more than 126,000 photographs, maps, manuscripts, texts, and sound recordings in addition to exhibits. Nearly 1,200 images of artifacts from early Chinese American settlements in Los Angeles and Santa Barbara are available, as is the entire run of El Clamor Publico, the city's main Spanish-language newspaper from the 1850s. Photographs document Japanese American relocation during World War II and photographs, documents, and oral history audio files record Korean-American history. The archive also includes Works Projects Administration Land Use survey maps and Auto Club materials. A related exhibit, "Los Angeles: Past, Present, and Future", offers collections on additional topics, including discovery and settlement, California missions, electric power, "murders, crimes, and scandals," city neighborhoods, cemeteries, Disneyland, African American gangs, and the Red Car lines.