Beginning with the Rocky Mountain News' first edition published in April,1859, the collection contains hundreds of newspapers from towns extant and defunct across the state. Over 250 titles of currently published newspapers are available in the library. Personal papers, diaries, and correspondence of famous as well as little-known individuals provide insight into life in Colorado from a very singular point of view. Manuscripts are by their very nature unique to a repository, since they weren't produced in multiple copies. The collection consists of thousands of maps ranging in size from a few inches square to rolled railroad maps many yards long.
Maps cover Colorado and the Rocky Mountain West from time of Spanish exploration to the present.
The Society's collection of Sanborn Insurance Atlases include detailed views of streets and buildings for hundreds of Colorado towns from the 1880s. The maps show building materials, street name changes, placement of hydrants and other fire information, names or types of buildings in a neighborhood, lot numbers, and much more. In the larger cities, the maps were updated periodically to show the growth of the city over time. There are over 80 volumes in the set providing easy access to a vast source of Colorado and western history articles. The Society has theatre programs, menus, sheet music, valentine cards, and brochures and pamphlets on subjects ranging from local festivals to Zang's Brewery.