Best known for his Civil War photographs, Alexander Gardner (1821-1882) also created two extraordinary bodies of work depicting the transformation of the American West: Across the Continent on the Kansas Pacific Railway and Scenes in the Indian Count...

Clarence King's Survey, undertaken between 1867 and 1872, covered a vast swathe of terrain, from the border of California eastward to the edge of the Great Plains. It was the first survey to include a full-time photographer – Timothy O'Sullivan – who...