Carleton Watkins traveled to the Yosemite Valley in 1861 with a wet-plate camera and large, fragile glass plates, taking what would become the first of hundreds of “mammoth-plate” prints of the region. Mammoth plates were so called because the glass plates were the same size as the large final prints, which allowed for outsized photographic prints before the development of enlargers. Some of Watkins's photographs were used to sway President Lincoln to designate Yosemite as the first state park in 1864.