Johnson's work focuses on the history of slavery, capitalism, white supremacy, Black resistance, and US imperialism.

He developed the book over years, beginning with ideas he explored first in a seminar on Southern History taught by Nell Irvin Painter.

[citation needed] In this book, Johnson took up and engaged with many of the themes which had occupied historians of slavery in the thirty years before it was published.

In this way, it investigated the daily reproduction of racist ideas about medicine, management, and sexuality in the institution that was at the heart of the slaveholding economy.

By recovering traces of slaves' efforts to shape their own sales, it altered the central symbol of slavery's brutality by placing it in a history of opposition, resistance, and manipulation.

In noting the vulnerability of slaveholders' identities, which were dependent upon slaves for their performance, Johnson sought to explain the extraordinary violence that characterized all of antebellum slavery.

As Johnson put it “This daily dialectic of categorization and differentiation was the magic by which the traders turned people into things and then into money” (pg.11).

Despite the efforts of slave owners to make their salves more appealing for sale, Johnson explains how an 1829 Louisiana law made it illegal to separate children under the age of ten from their mothers.

Ironically most of the reasons made up by owners could be false so really, they were worthless statements, but the traders were only bound by the story they wrote down and signed.

It is a historiographical and theoretical consideration of the notion of "agency" central to a large body of scholarship in the Humanities and Social Sciences.

"On Agency," is a critique of the crypto-liberal philosophical premises of progressive historiography, and a call for what the historian Richard White termed a more "radical" approach to the writing of history.

The piece suggests that, while the nineteenth century developed a hard-and-fast ideological distinction between the two which has made its way into the work of many subsequent historians, in historical fact slavery and industry were so deeply intertwined that they should be considered as differentiated aspects of a single economic system.

River of Dark Dreams: Slavery and Empire in the Cotton Kingdom was published by Harvard University Press in 2013.

In it, Johnson seeks to empirically substantiate some of the conceptual arguments made in his articles from the preceding decade, as well as to resituate the historiography of nineteenth-century slavery in the history of the global economy of the nineteenth century.

Among his principal scholarly influences, Johnson cites Du Bois, Cedric Robinson, Nell Irvin Painter, Robin D. G. Kelley, David Roediger, George Lipsitz, Daniel Rodgers, Richard White, Lisa Lowe, Adam Green, and Stephanie Smallwood.

Writing at length in the Boston Review, Johnson has recently invoked the models of Du Bois and Cedric Robinson in proposing that the historiography of slavery be reframed around the idea of "racial capitalism."

[8] The central claims in Johnson/s prize-winning River of Dark Dreams have been criticized as "dubious" and "grossly exaggerated" by the historian Philip Morgan.

[9] By way of contrast, the historian Thavolia Glymph hailed the book as "a profoundly learned and magisterial work of synthesis and path-breaking new scholarship.