A very large and striking map with considerable visual impact in original watercolor. Excellent detail of railroads including the Union Pacific showing two parallel routes one ending in Denver the other a little north and heading into Wyoming and off the map. Dozens of forts located. Numerous routes of explorations and surveys are drawn in. Areas roamed by principal Indian Tribes are shown. Warren's extensive knowledge of the area and his skill as a cartographer are obvious in this large, detail-filled map. Geology of eight different groups is indicated by hand coloring. Geology was provide by Dr. Ferdinand Hayden, then Professor of Geology and Mineralogy at the University of Pennsylvania, and only 4 years prior to his famous trip of exploration into Yellowstone that resulted in Yellowstone becoming the first National Park in the United States. We have never seen this map nor can we locate any reference to it.

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Condition: A

Close at the left side, as issued. Reinforced with archival tissue and pressed.