Volume 3 surveys the economic history of the United States, Canada, and the Caribbean during the twentieth century. Its chapters trace the century's major events, notably the Great Depression and the two world wars, as well as its long-term trends, such as changing technology, the rise of the corporate economy, and the development of labor law. The book also discusses agriculture, population, labor markets, and urban and regional structural changes.

By the date of publication of this volume the entire twentieth century will have passed before our eyes and become a reputable period for historical study. The fact that the essays in this volume are concerned with recent events means that they sometimes reach conclusions more tentative than those in earlier volumes, where more of the historical dust has settled and the long-term implications of certain events and changes are reasonably clear. While the terminal dates of most papers are similar - World War I and the ending of the century — some cover the period from the start of the century. There is also some discussion of the twentieth century in two of the chapters in the preceding volume, Freyer on business law and Fishlow on transportation.

Volume III differs from the earlier volumes in that it contains two chapters on specific events, having no clear precedent in the previous volumes, but that were crucial in shaping the twentieth century. These events have social, political, and economic impacts influencing not only the United States but the entire world. The century was marked by one severe, worldwide depression lasting about one decade and two major world wars involving numerous countries and drawing heavily upon human and nonhuman resources. Among the consequences of the Depression of the 1930s and World Wars I and II has been the greatly expanded role of the national government in the economy. The expanded nature of fiscal and monetary institutions, the greater use of deliberate policy controls, and the increased regulation of businesses and individual behavior were among the most dramatic changes of this century, making the U.S. economy of year 2000 very different from the economy of 1900.