For most privileged, professional people, the experience of confinement is a mere brush, encountered after a kid’s arrest, say. For a great many poor people in America, particularly poor black men, prison is a destination that braids through an ordinary life, much as high school and college do for rich white ones. More than half of all black men without a high-school diploma go to prison at some time in their lives. Mass incarceration on a scale almost unexampled in human history is a fundamental fact of our country today—perhaps the fundamental fact, as slavery was the fundamental fact of 1850. In truth, there are more black men in the grip of the criminal-justice system—in prison, on probation, or on parole—than were in slavery then. Over all, there are now more people under “correctional supervision” in America—more than six million—than were in the Gulag Archipelago under Stalin at its height. That city of the confined and the controlled, Lockuptown, is now the second largest in the United States.