Stereoscopic photographs, or stereoview cards, became popular in the 1850s as a form of entertainment for the masses. Stereoview cards are composed of two nearly identical images mounted side-by-side on a cardboard backing providing a viewing experience of the scene in 3-D. The card is viewed using a "stereoviewer" to bring out the 3-D effects of the photographic composition.
As stereoviews became commonplace and relatively inexpensive to produce, the cards emerged as souvenir items quite naturally. Images ranged from world views of cities, towns, monuments, parks, and other natural history attractions. The Liberty Bell was used extensively as a subject.