The importance of documenting explored lands was recognized early in the exploration of the American West. Pictures were necessary to describe what the land looked like in the unfamiliar North American continent. Without them, few would be able to visualize the vastness of the American plains. Thus, the United States government assigned artist Samuel Seymour to accompany an expedition to explore the region of the Yellowstone River. It was led by Major Stephen Long and set out in 1819. This exploring party ran into many difficulties. Although they were not able to travel to the Yellowstone River, they did cross the western plains and reached the magnificent Rocky Mountains, in what is now the state of Colorado (see Rocky Mountain National Park). Seymour made a watercolor drawing of the Rockies, and it was engraved for the official published report of the Long expedition, thus bringing the first known published image of the Rocky Mountains to the public.

Illustration: Samuel Seymour, artist and J. Clark, engraver. "Distant View of the Rocky Mountains," drawn 1820, engraving printed 1823 in Edwin James, Account of an Expedition from Pittsburgh to the Rocky Mountains Performed in the Years 1819 and 1820, by Order of the Honorable J.C. Calhoun, Secretary of War, under the Command of Major Stephen H. Long of the U.S. Top. Engineers, vol. 1 (London: Longman, Hurst, Rees, Orme and Brown, 1823). McCracken Research Library, Buffalo Bill Historical Center, Cody, Wyoming.