This primary source comes from the Records of the Office of the Chief of Engineers.
National Archives Identifier:
5900021Full Citation: Map of Lewis and Clark Track Across the Western Portion of North America from the Mississippi to the Pacific Ocean; ca. 1806; Records of the Office of the Chief of Engineers, Record Group 77. [Online Version, https://docsteach.org/documents/document/map-lewis-clark-track-across-usa, May 6, 2024]