An African migrant stranded in Costa Rica bathes at a makeshift camp at the border between Costa Rica and Nicaragua, in Penas Blancas, Costa Rica, July 14, 2016. Thousands of African migrants are currently stranded in Costa Rica after they were denied entry into neighbouring Nicaragua, which they have been using as a crossing point in order to reach the United States. According to the Costa Rican Red Cross, most of these people from Africa, Asia and Haiti. It has been reported that many of them paid smugglers to reach Central America. However, when they arrived at the border gates, they were denied entry and were left with nowhere to go. (Photo by Juan Carlos Ulate/Reuters)

Christian families living in a refugee camp stand under a tree in Kaga-Bandoro, Central African Republic, Tuesday February 16, 2016. Refugees in the north of Central African Republic say they hope the new president will bring peace but no one is heading home just yet. Thousands are still living in displacement camps in Kaga-Bandoro, a stronghold of the former Muslim rebel group known as Seleka that was in power for nearly a year. The one-time rebels say they are waiting to see how the election turns out before taking any action. (Photo by Jerome Delay/AP Photo)

An Anti-Balaka fighter, member of a militia opposed to the Seleka rebel group, puts a knife to his throat showing what he would do to any Seleka, on the outskirts of the Boy-Rabe neighborhood in Bangui on December 14, 2013. France raised alarm on December 13 over worsening violence in the Central African Republic, as UN chief Ban Ki-moon urged warring Christians and Muslims to stop the bloodshed that has left more than 600 dead in the past week. (Photo by Ivan Lieman/AFP Photo)

Cattle are the most important way of livelihood for the Karamojong: they provide milk, meat, blood and money when sold, Karamoja, Uganda, February 2017. (Photo by Sumy Sadurni/Barcroft Images)

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)

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

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)