Walter Johnson is Winthrop Professor of History and a professor of African and African American studies at Harvard University. His first book, Soul by Soul: Life inside the Antebellum Slave Market (1999), uses the slave market as a way to think about the fantasies, fears, negotiations, and violence that characterized American slavery. His most recent book, River of Dark Dreams: Slavery and Imperialism in the Mississippi Valley (2013), retains a focus on the immediate experience of slavery and mastery. It also embeds the history of American slavery in the histories of global capitalism, especially the cotton trade and the Atlantic money market, and U.S. imperialism, including the Louisiana Purchase, the illegal invasions of Cuba and Nicaragua in the 1850s, and the effort to reopen the Atlantic slave trade on the eve of the Civil War. He has also written a series of essays about social and historical theory relating to the history of slavery in the United States; on the idea of "agency" as the organizing theme of scholarship; on notions of time; on theories of capitalism and slavery; and on the idea of reparations for slavery as a historical narrative. Johnson grew up in Columbia, Missouri, and is currently writing a book about the history of St. Louis from Lewis and Clark to Michael Brown.