What is the importance of Washington Park in the nonfiction book, Gang Leader For a Day?

Sudhir visited Washington Park where some old-timers hung out every day. These African-American men had seen a lot in their times that were relevant to Sudhir’s studies. They had seen racism, poverty, the onset of the drug culture and the emergence of the notorious South Side gangs. One man told Sudhir that blacks and whites would never live in equality. The blacks lived in a world that was within the white world.