How does Stevenson argue that the modern day prison system acts as a continuation of slavery?

Stevenson returns to the theme of mass incarceration—i.e. locking Americans in prison at historically unheard-of rates—throughout the memoir. He details the dramatic rise in the number of people imprisoned since he began his legal career in the early 1980s. He also explores how many people are imprisoned for nonviolent offenses, as well as children serving adult life sentences. Impoverished people and people of color are over-represented in prisons, and this imprisonment is profitable to the companies that build, own, and maintain prisons. Stevenson traces a historical line from this practice back to chattel slavery in the U.S. In part due to the Equal Justice Initiative's social justice work, by 2014, mass incarceration rates had stabilized.