The Face of Slavery &  Other African American Photographs -- American Museum of Photography
What we call "history" is born from a collage of glimpses and images, insights and documents. And while this Gallery does not presume to tell the comprehensive story of early photography and African Americans, it does offer tantalizing glimpses into the past. During the half-century covered by these photographs, African Americans fought slavery, withstood brutal racial hatred, and struggled to escape from poverty. Sometimes the camera was their ally... sometimes it was an instrument of prejudice... but often it was an observer, recording the images that we recognize today as the raw material of history.
http://www.photographymuseum.com/faceof.html