Photographs by Horace Poolaw at National Museum of the American Indian

Since 2008, the exhibition’s organizers — Nancy Marie Mithlo Chiricahua Apache, chairwoman of American Indian studies at the Autry National Center, and Tom Jones Ho-Chunk, a professor of photography at the University of Wisconsin-Madison — have painstakingly restored Mr. Poolaw’s fragile black-and-white negatives and made prints.