From the Introduction: "The 156 items described in this list comprise all the maps in the custody of the Cartographic Archives Division that can be identified as having originated before 1790, as being copies or facsimiles of pre-1790 maps, or as later maps that portray areas or events from the pre-1790 period. The list describes many historically significant items that can, in a real sense, be considered the foundation upon which the vast Federal mapping program was subsequently built. Every new map draws heavily upon the concepts, data, and techniques established by its cartographic...