The Preface introduces the book’s main subject and defines some key concepts. Residential segregation exists across the United States. There is a common belief that segregation is de facto, or caused by individual choices. In this narrative, when African Americans move into predominately White neighborhoods, racially prejudiced people leave in what is called white flight. This is coupled with the narrative that Black people prefer Black neighborhoods. De facto segregation is part of the story, but only a small part. De jure segregation, or segregation enforced by law and public policy, plays a much more significant role. Governments and courts supported and implemented segregation in residential housing, even though segregation violates the Constitution and the Bill of Rights, as the Fifth Amendment prohibits unfair treatment. After the Civil War, the Thirteenth Amendment was enacted to prevent slavery or treating African Americans as second-class citizens, while Fourteenth Amendment prohibits states from treating people unfairly or unequally. In 1968 the Fair Housing Act banned racial segregation. However, neighborhoods remain segregated across the United States.