How often do we see African-Americans on crime fiction paperbacks in the 1940s and 1950s. Experts, help me out here!
In this case I think the most striking individual is the African-American railway porter. His glance at the couple directs attention to them (and particularly the woman's fearful reaction to what she sees in the passenger compartment), but he holds attention in his own right.
|a Pullman porter
On African-American porters see this interesting article by article by Lawrence Tye, author of the book Rising from the Rails: Pullman Porters and the Making of the Black Middle Class (2004).