Housing and racism
During the 20th Century, there was a huge amount of racism in the housing sector. This meant that black families were unable to move into "white" neighbourhoods due to prejudice. Although this kind of segregation was not defended by the law, policymakers did little to uphold these laws in practice, meaning a lot of underhand racism dominated the housing sector. For example, estate agents would warn white families about black neighbourhoods and discouraged them from moving there.
De Jure vs. De Facto change
This novel emphasizes that just because a law has changed, doesn't mean it will make a practical difference. The housing sector in the 20th Century is a good example, as segregation was still upheld after the laws were changed, as people's attitudes remained the same.