"Amanda and her Cousin Amy": Mary Ellen Mark photographed Amanda Marie Ellison, 9 (right), and Amy Minton Velasquez, 8, in Valdese, N.C., in 1990. Courtesy of Mary Ellen Mark Studio and Library hide caption

itoggle caption Courtesy of Mary Ellen Mark Studio and Library

Vanity Fair's Twitter page shows its July cover with Caitlyn Jenner. The issue and photo shoot had to be planned in secret. Mladen Antonov/AFP/Getty Images hide caption

itoggle caption Mladen Antonov/AFP/Getty Images

Rekha is one of the many caged prostitutes Mary Ellen Mark came to know as she photographed in the red-light district of Mumbai. Courtesy of Mary Ellen Mark Studio and Library hide caption

itoggle caption Courtesy of Mary Ellen Mark Studio and Library

Carrot pullers from Texas, Oklahoma, Missouri, Arkansas and Mexico. "We come from all states and we can't make a dollar in this field noways. [sic] Working from seven in the morning until twelve noon, we earn an average of thirty-five cents." California, February 1937 Dorothea Lange/Library of Congress hide caption

itoggle caption Dorothea Lange/Library of Congress

Army Spc. Jerral Hancock sits for a portrait with his son Julius. It is believed that Hancock was trapped under the wreckage of his Army tank in Iraq for half an hour before he was rescued. Courtesy of David Jay/Unknown Soldier hide caption

itoggle caption Courtesy of David Jay/Unknown Soldier

Photographer Sally Mann drives with her greyhound, Honey, in the early 2000s. Michael S. Williamson/Courtesy of Michael S. Williamson hide caption

itoggle caption Michael S. Williamson/Courtesy of Michael S. Williamson

"Question Bridge: Black Males" attempts to represent black male identity in America via a video question-and-answer exchange. At top center is Jesse Williams, the project's executive producer. Question Bridge: Black Males hide caption

itoggle caption Question Bridge: Black Males