Ruby is set in a changing American South. A century after the emancipation of enslaved people, racial segregation in the South was still the norm, enforced by Jim Crow laws that remained in place until the 1960s. From the 1960s to the 1970s, the decade in which the novel takes place, the Civil Rights and Black Power movements were in full swing. Ruby focuses on the nonviolent Civil Rights Movement, in which Black Americans protested racial segregation and discrimination through marches, sit-ins, and other social actions. Famous highlights of the movement include the Montgomery Bus Boycott and the March on Washington led by Martin Luther King, Junior. The movement achieved massive progress—throughout the 60s, several landmark rulings were made against segregation, and laws like the Civil Rights Act of 1964 criminalized racial discrimination.

Bond weaves this historical background into the setting of Ruby, using it to further the recurring motif of the way the past influences the present. Liberty Township is an all-Black town in the South. Its landscape is saturated with memories of slavery, and despite the progress made by the Civil Rights Movement, its residents still experience racial oppression. As a Black woman, Ruby deals with the dual oppressive forces of racism and sexism.