The demographic development which was the subject of the last chapter, the massive growth of the American population in the latter half of the nineteenth century, had historic consequences for the national economy. In the fifty years from I860 to 1910, the population of the United States nearly tripled, and so did the size of the market for goods and services which it supported. One particular component of growth in this period – a great increase, by immigration, in numbers of young adult males – led to an expansion of the country's labor force which more than matched the enormous increments in total population. Together with advances in technologies of production and transportation, and increases in capital investment and personal income, these structural changes in American society made possible the realization, by the outbreak of the First World War, of a trend which had begun in the decades before the Civil War, a trend toward an economy based predominantly in manufacturing (North, 1965: 693–700; cf. Diamond, 1963; Hays, 1957:4–17; Ross, 1968:25–37).

“Judged by the total volume of its industrial output,” one economic historian (North, 1965: 702) writes, “the United States was, by 1914, the most industrialized nation in the world.” A sociologist illuminates the more far-reaching, if intermediary, steps in the process by which industrial supremacy was achieved: