Where millions enter America
Stereographs, an early form of three-dimensional photograph, were a popular form of education and entertainment in the latter part of the nineteenth century. The stereograph, otherwise known as the stereogram, stereoptican, or stereo view, was the nineteenth-century predecessor of the Polaroid, with an imaginative flair. Two almost identical photographs were placed side by side on a piece of cardboard. These images were meant to be viewed with a stereoscope, an instrument attributed to Oliver Wendell Holmes circa 1859. Stereography immediately became a commercial success. Stereographs crossed class lines, affordable to rich and poor alike, so these images had a very large audience.