This book has been written to provide a relatively brief (and, I hope, readable) overview of post-1750U.S. foreign relations. Chapters' lengths increase markedly after 1890. The pre-1890 sections, however, include the material needed to understand the first century of those foreign relations; all or part of those chapters can be used as introductory assignments in a one-semester post-1890 class.
The title is taken seriously. As Professor Thomas A. Bailey once observed, the United States was a world power at the birth of its independence in 1776. Then, if not before, the American age began because the country already ranked with the great European nations in terms of territory, population, economic strength, and natural resources, not to mention ambition. This survey tries to develop several themes that tie 250 years together, make sense of them, and give students and teachers starting points for discussion. The most obvious theme is the landed and commercial expansion that drove the nation outward between 1750 and the 1940s. Then, resembling other living things that age, the country's power began a relative decline after the mid-1950s. Americans have yet to understand and come to terms with the causes and consequences of that decline, although presidents from Kennedy through Reagan have, in varying ways, shaped their policies so that the country could adjust to this new world.
The book's second theme is the steady centralization of power at home, especially in the executive branch of government after 1890. This centralization occurred not merely because of the normal quest of human beings for power, but also because the foreign policies that Americans have desired since the nineteenth century are most effectively carried out by a strong presidency. There are no recurring cycles in this book, only the long rise and the relative decline of U.S. power, and the steady accretion of authority by presidents because of the way Americans have wanted to exercise that power. U.S. diplomatic history has often been written as if constitutional questions ceased to be important after 1865; this volume tries in small part to rectify that neglect.
A third theme is "isolationism," which means in U.S. history not withdrawal from world affairs (a people does not conquer a continent