Poland Spring House, William Henry Jackson photograph

William Henry Jackson (1843-1942) was an American painter, photographer, and explorer who is best known for his pioneering work in documenting the American West. He was born in Keeseville, New York, and after serving in the Union Army during the American Civil War, he became interested in photography. Jackson worked as a photographer for the United States Geological Survey, and he was a member of several expeditions to the West, including the Hayden Geological Survey of 1871. During these expeditions, he produced a large number of photographs that helped to document the landscape and the Native American cultures of the region. Jackson's photographs were instrumental in promoting the idea of creating national parks in the United States. He was also one of the founding members of the Detroit Photographic Company, which produced a large number of postcards and other commercial products based on his photographs.

Mammoth plate photographs are photographic prints made through contact printing a photographic print from a large glass plate negative, usually 18 by 21 inches, but may vary in size from 15 by 18 inches to 22 by 25 inches, which were used in the late 19th and early 20th centuries to create very large photographic prints. The plates were typically made of glass and coated with a light-sensitive emulsion and were commonly used for landscape and architectural photography, as well as for portraiture. Mammoth plates were particularly popular in the United States in the 1880s