by Lieut. G.K. Warren from the explorations made by him in 1855 & while attached to the staff of Brev. Brig. Gen. W.S. Harney, commg. Sioux Expedn. and in 1857 under the direction of the Office Explns. and Surveys, Capt. A.A. Humphreys in charge ; exhibiting also routes reconnoitred & surveyed by Capts. Lewis & Clark, U.S.A. ... [et al.].
Covers North Dakota, South Dakota, Nebraska, and portions of Minnesota, Iowa, Missouri, Kansas, Colorado, and Montana.
Relief shown by hachures and spot heights.
In upper left margin: "35th Congress, 1st Session, printed by order of the U.S. Senate."