Keystone-Mast Collection

The Keystone-Mast Collection comprises over 350,000 stereoscopic photographs and negatives that depict the world between the late-nineteenth and mid-twentieth centuries. Firms represented in Keystone-Mast include Keystone View Company, Underwood and Underwood, B.W. Kilburn, H.C. White Company, Universal Photo Art Company (C.H. Graves), American Stereoscopic Company, W.H. Rau, Berry, Kelley and Chadwick, and George Rose. The photographs are generally not stereo cards, but contact prints from the original negatives, annotated by Keystone staff and photographers.