. >> reporter: images were mortalized in songs, like "strange route", performed by billy halliday. ♪lack bodies swinging in the breeze ♪ ♪ change who hanging from the poppy trees ♪ . >> i think of america as a tree and i think of african-americans hanging from the tree as strange fruit. >> reporter: these are lynching victims. >> yes, so if america is a tree and african-americans are a strange prut. the talk is analogous to the growth ring. the talk, as this growth ring tells us about the racial customs of country over time. >> in my research, what i find is in each growth ring the talk it different. the second is a civil rights movement. before the civil rights legislation, you have to imagine that's emancipation up until civil rights. that's the period of racial terrorism. talk there conveys messages that communicate to children that they need to show fear and deference in the interaction with figures of authority, and white people. >> reporter: after the civil rights act was passed, the talk under went a change protecting new legal perspectives, changes that were celebrated in pop