A British Museum representative poses for photographs next to Andy Warhol's “Mao”, left, and Jim Dine's “Drag: Johnson and Mao” which feature in “The American Dream: pop to the present” exhibition during a media photocall at the British Museum in London, Monday, March 6, 2017. The exhibition, which opens to the public from March 9 and runs until June 18, charts modern and contemporary print making. (Photo by Matt Dunham/AP Photo)

A statue of a man sleepwalking in his underpants is surrounded by snow on the campus of Wellesley College, in Wellesley, Mass., Wednesday, February 5, 2014. The sculpture entitled “Sleepwalker” is part of an exhibit by sculptor Tony Matelli at the college's Davis Museum. (Photo by Steven Senne/AP Photo)

Artist Pyotr Pavlensky sits on the wall enclosing the Serbsky State Scientific Center for Social and Forensic Psychiatry after he cut off a part of his earlobe during his protest action titled “Segregation” in Moscow October 19, 2014. Pavlensky protested against the usage of forensic psychiatry for politically motivated purposes. He cut off his earlobe to demonstrate how authorities could “cut off” an unwanted individual from society by using psychiatric and medical diagnosis to forcefully send a person to a penitentiary hospital, according to Pavlensky. (Photo by Maxim Zmeyev/Reuters)

Kaw-Claa, a Tlingit native woman in full potlatch dancing costume, 1906. (Photo by Case & Draper/Buyenlarge/Getty Images)

At the beginning of the 20th century, Edward S. Curtis set out to document what he saw as a disappearing race: the Native American. From 1907 to 1930, Curtis took more than 2,000 photos of 80 tribes stretching from the Great Plains to the Pacific Northwest and Alaska. He then published and sold these photos, along with narrative text, in 20 volumes of work known as “The North American Indian”. It is one of the most significant collections of its kind, “probably the most important photographic document of its age and its topic,” said Jeffrey Garrett, associate university librarian for Special Libraries at Northwestern University. (Photo by Edward S. Curtis)

Tank crew standing in front of M-4 tank, Ft. Knox, Kentucky, June, 1942. (Alfred Palmer/OWI/LOC)

Frank A. Rinehart, a commercial photographer in Omaha, Nebraska, was commissioned to photograph the 1898 Indian Congress, part of the Trans-Mississippi International Exposition. More than five hundred Native Americans from thirty-five tribes attended the conference, providing the gifted photographer and artist an opportunity to create a stunning visual document of Native American life and culture at the dawn of the 20th century. Photo: Little Bird, Arapahoe, 1899. (Photo by Frank A. Rinehart)

Gus Palmer (Kiowa, at left), side gunner, and Horace Poolaw (Kiowa), aerial photographer, in front of a B-17 Flying Fortress. MacDill Field, Tampa, Florida, ca. 1944. (Photo and caption by 2014 Estate of Horace Poolaw)