In Western history, the middle passage refers to the Africa-to-Americas leg of the triangular trade that allowed Europeans and Americans to exchange goods for slaves. While the Republic is crossing the Atlantic on the middle passage part of its journey, Johnson uses the middle passage as a figure to stand in for the violent, sometimes deadly process of forcing enslaved African people to become Americans who could never be legally recognized as such. This in-between state means that people caught up in the middle passage are cultural hybrids whose language, belief systems, and social organizations undergo rapid changes for the sake of survival.

Johnson also uses the middle passage as a figure for the in-betweenness in Rutherford’s state of mind. As a stowaway and an ex-slave in a slaveholding society, Rutherford is forced to float back and forth between different spaces and groups. His ability to serve as an Allmuseri–English interpreter reinforces his role as a symbol for the peculiar situation of black people in a slaveholding society.

The Republic is the central symbol of the novel. Rutherford describes the ship as a floating wreck that is constantly coming apart at the seams and thus has to be constructed as it is underway on the Atlantic.