Research Department, Federal Reserve Bank of Richmond, Richmond, VA 23261; and

This paper was begun while both authors were visiting the Graduate School of Business of the University of Chicago. The paper has benefited greatly from presentations at the American Economic Association Meetings, the Federal Reserve Bank of Richmond, James Madison University, the Minneapolis Federal Reserve Bank Conference On Growth and Development, Northwestern University, Ohio State University, Rutgers University, the Stanford NBER Growth Conference, the University of British Columbia, the University of Chicago, the University of Kentucky, the University of Rochester, the University of South Carolina, the University of Virginia, Virginia Polytechnic University, and the Wharton School of the University of Pennsylvania. Maddison (1982), p. 4