A rush to uncover western fossil riches began in 1871, the same year Yellowstone and the Grand Canyon were being explored. Reports of undocumented fossil types by these new expeditions lured major scientists into the great outdoors regardless of the hardships. One of the most renown of these new explorers was Othniel Charles Marsh, a professor of paleontology at Yale College in New Haven, Connecticut.
The illustrated cover was posted from Red Cloud Agency No.2, Nebraska on 25 June 1875 and is addressed to Professor Charles Marsh at Yale College in New Haven, Connecticut. The script docketing on the side indicates the letter was posted by H.E. Farnam using an imprinted envelope of J.W. Dear, an Indian trader at the agency.