William Freehling, The Road to Disunion, vols. 1 and 2 (New York: Oxford University Press, 1991 and 2008).
James M. McPherson, Battle Cry of Freedom: The Civil War Era (New York: Oxford University Press, 1988).
David Potter, The Impending Crisis: America Before the Civil War, 1848–1861 (New York: Harper Perennial, 1977).