This collection consists of postcards of prisons and reformatories from forty-five states. Also included are a few postcards of convict ships, torture devices and foreign prisons. These postcards have been collected by Dr. William G. Hinkle over a twenty-five year time period from various vendors. The collection also includes numerous photographs of the Indiana State Prison and the Cambria County, Pennsylvania Jail taken by Dr. Hinkle.

Most of the postcards were not dated, so dates were derived from postmarks when available. The title is the name of the institution as it appeared on the postcard and 'prison' and 'penitentiary' are sometimes used interchangeably.