He has written on the American Revolution and American Civil War. He is the author of four books on American history including ''A Mighty Empire: The Origins of the American Revolution'' (1988); ''Divergent Paths: How Culture and Institutions Have Shaped North American Growth'' (1996); and ''New World Economies:the Growth of the Thirteen Colonies and Early Canada'' (1998).
His book, ''Clash of Extremes: The Economic Origins of the Civil War'' (2009), argues that "more than any other reason, the evolution of the Northern and Southern economies explains the Civil War."
Most recently, Egnal has turned his attention to US novels and the value of Big Data in understanding this literature. See his essay, "Crunching Literary Numbers," in the Gray Matter column of the New York Times, July 12, 2013.
