Two crucial elements combined to foster the rapid expansion of industrialization: an army of freshly minted entrepreneurs and a stunning array of new technologies that literally changed the face of America. The two were inseparable and indispensable to each other. For alert entrepreneurs, new technologies became not only the key to whatever industry they entered but also the source of a multiplier effect that increased both the scale of their operation and the size of their fortunes. However, technologies could develop only when entrepreneurs sensed their potential, took hold of them, and employed them in ways that ultimately embedded them as the foundation of the American way of production. This mutual dependence proved a potent catalyst for rapid economic expansion.

This interaction between men and machines also produced a profound change in the way people looked at the world around them. Machines do not suddenly knock at society's door and ask to be put to work; nor can they be ordered to their tasks like obedient servants. Their presence in growing numbers, and their increasing productivity and sophistication, required dramatic changes in the structure of the economic system, and these in turn wrought unexpected changes in society itself.