Statistics for occurrence #1 of “Alton, Illinois” in chapter 1.3 of The Photographic History of The Civil War: in ten volumes, Thousands of Scenes Photographed 1861-65, with Text by many Special Authorities, Volume 7: Prisons and Hospitals.:

...Fort Warren in Boston Harbor, Fort Lafayette at New York, and Castle Pinckney at Charleston are types; second, buildings previously constructed to restrain criminals, of which the old penitentiary at Alton, Illinois , was the most important; third, buildings constructed for various purposes, turned into prisons with more or less alteration, typical of which were the Old Capitol at Washington, the Gratiot Street P...
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