To Love Mercy by Frank S. Joseph

The worlds of a Black family and a Jewish family unexpectedly collide in 1948 Chicago after a bizarre accident leaves a Black boy injured. Sass Trimble, from Bronzeville, "Chicago's Harlem," and Steve Feinberg, a Jewish boy from well-to-do Hyde Park, get on a bus together and get lost in the city. Once free from the neighborhoods that have defined them, the boys explore the city together with enthusiasm, while their families tear each other apart in fear. Steve and Sass spend a day and a night getting more and more lost, and along the way they also lose their inclination to go home. At last the boys discover Riverview -- then "The world's largest amusement park" -- where racism catches up to them.