Tommy Tester faces danger any time he leaves Harlem and crosses into a white section of the city. In the late 19th and early 20th centuries, urban planning in most major American cities was based on segregation. In the South Jim Crow, laws formalized segregation, and in the North, where such laws did not formally exist, redlining ensured that blacks and whites would live in different parts of the city. On their first meeting, Ma Att cautions Tommy not to be in Queens after sundown. This is a reference to “sundown towns,” all-white neighborhoods that enforced segregation through discriminatory laws, violence, or intimidation. The police harass Tommy for being in Flatbush during the day, but white train passengers question him and white teens chase him when he goes there at night. This shows that even if the police are not present to enforce such laws, or if such laws do not formally exist, the racist white population informally enforces them.

Border crossing of whites into black areas is undesirable, too, but the individuals who do so do not face immediate danger. Robert Suydam’s frequenting Red Hook and inviting a “swarthy army” (89) into his home so alarms his family that they doubt his sanity.