The photographic holdings of the Yale Collection of Western Americana span the history of photography from daguerreotypes and salted paper prints to the work of contemporary photographers. The collections, which include examples of virtually every format and photographic process, document the people and places of the Trans-Mississippi West, as well as the social, cultural, and economic history of photography in and about the American West. Subjects include Native Americans, Western landscapes and city views, National Parks, geological surveys, economic development (mining, lumbering, industry). Materials include family photography, photographically illustrated books, and stereographic photography.

These materials support research about individual photographers, about the spread of photography in the West, and about the evolving visual representation of the West and its inhabitants. The collections include both public and private photographs; that is, those made for sale and those made for personal consumption. It also includes extensive holdings of portrait photography of Native Americans made in eastern cities, as well as photographs of Native American communities from the eastern United States.

The collection is one of the largest devoted to the social and cultural history of photography in the American West. Collected to support research, teaching, and learning about the history and culture of the American West and about American history in general. the collection brings together in one place many works often held elsewhere in smaller, less focused collections and includes several unique archival collections as well as individual images that seem to be unique.