Hi there! You asked about the themes of poverty, racism and crime in Claude Brown's novel Manchild In A Promised Land.
I will address each theme separately:
Brown portrays poverty as an impediment to upward mobility, and as a self-perpetuating cycle of despair and self-hatred. Poverty is both portrayed as a social and material handicap. Sonny, the narrator, not only resorts to stealing to purchase life's necessities, he also has to endure the emotional morass of an unstable home. He endures physical abuse from his father with a helpless mother looking on. The poverty and the lack of a healthy home environment steals the innocence of many Harlem youth and burdens them with their own self-defense and self-care before they are able to mentally grasp the gravity of their situation.
Racism is portrayed as both institutionalized and societal. Sonny is sent to the Wiltwyck School For Boys, founded by Eleanor Roosevelt, to whom Brown dedicates Manchild In A Promised Land. Brown portrays for us the utter shame and helplessness in being relegated to a school for troubled African American boys; it is only due to the sincere and conscientious efforts of the school administrator, Mr.Papanek, that Sonny is able to start his journey of pulling himself out of the mire of poverty and crime. When he finally leaves Harlem, he learns that even though he has no future with a white girl with whom he falls in love, he will never be blinded again by being overly conscious about color. The fact that he is able to love a white girl proves his humanity, and even though her parents send her away in disapproval, he learns that a strong sense of self is the key to meaning in his life as he explores his African heritage and various religions, from Coptic Christianity to Islam.
Brown portrays crime as one of the biggest handicaps Harlem youth had to contend with in the 1950s. Crime is only attractive because it is the means to an end. It is the means of survival; low wages were a contributing factor to the high crime rate among angry and disillusioned African American youth in Harlem in the 1950s. Yet, there is a silver lining to Brown's story; education is the key to Brown's Sonny making his own way out of the never-ending and soul-destroying environment of drugs, police brutality and death.