His research is focused on the social history of the United States, particularly the history of black Americans in the 19th and 20th centuries. His research has been published in collected essays and in journals such as the Revue française d'études américaines , Canadian Review of American Studies , Indiana Magazine of History , Canadian Journal of History / Annales canadiennes d'histoire , and Histoire sociale / Social History . He is currently working on the history of the civil rights movement in the United States (1850-2000).