How did the United States transform itself from a largely agrarian economy to a powerhouse on the world stage and how did it happen so fast? We’ll spend this hour with H.W. Brands, the Dickson, Allen, Anderson Centennial Professor of History at the University of Texas in Austin and author of the new book “American Colossus: The Triumph of Capitalism, 1865-1900” (Doubleday, 2010).