According to this page of the National Archives Catalog:
The photographs in this series were taken by Ansel Adams for a Department of the Interior mural project, the theme of which was nature as exemplified and protected in the National Parks.
In the mid-1930’s, Secretary of the Interior Harold Ickes conceived the idea of commissioning painted murals for the department’s headquarters building in Washington, DC. Impressed by Adams’ work, Ickes later broadened the scope of the project to include mural-size photographs and recommended Adams for the photographer. According to Adams, in Ansel Adams, An Autobiography, he was “appointed at the maximum annual salary then allowed for any position not subject to congressional approval: twenty-two dollars and twenty-two cents a day for no more than 180 days’ work a year, plus five dollars per diem expense…” Adams began his travels to the parks in October 1941 and a year later submitted the prints in this series to Interior. None of the photographs, however, were ever reproduced as murals as the project was halted during World War II and never resumed.
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