The economic growth of the United States, although vigorous throughout the span of the nineteenth century, did not progress without serious interruption. Even if we disregard familiar business cycles, American economic history does not trace out a smooth path of industrialization and development or a consistent response to the challenge of the frontier. Rather, it seems that American development is best described as occurring in waves, each dynamic crest of which was followed by an equally stagnant, but shorter, period of depression, unemployment, and price deflation.
These long swings in the economic growth of the American states usually required two decades to run their course and left their mark upon many facets of our economic and social history. The rate at which population grew to fill our boundaries reflected these alternations in the pace of American development, not only in natural increase but also in the willingness of European immigrants to sever ties with the Old World and to accept the challenge of the New. Nor was the pace of the Western exodus unaffected by the long swing. In every upsurge of rapid growth, internal migration quickened, public land sales on the frontier assumed immense speculative heights, and the romantic expansion of the railroads progressed at feverish levels. Similarly with every stagnant or depressive period that followed, house building