Lefty Lewis: A kind-hearted traveling musician, who becomes a mentor and father figure to Bud.
Herman E. Calloway: A wealthy car magnate in Grand Rapids Michigan. He is also the father of toddler Dizzy, but not the biological father of Bud Caldwell.
Todd "Dizzy" Dewey Homer Calloway: The infant half-brother of Bud who was born with a clubfoot.
Miss Thomas: A librarian in Flint, Michigan, who helps Bud research the history of the Herman E. Calloway and his family.
Miss Hill: A social worker who initially places Bud in an orphanage and later returns him to Lefty.
Jim Crow: A racist segregation law prohibiting African Americans from sitting with white people on trains and buses.