226 INDUSTRIAL REVOLUTION AND WAGES

may be said, however, with some force, that altho these elements
 may account for the long-time growth of industry,
they do not entirely explain the recent rapid increase in output
 per worker. It is, nevertheless, true that these natural
features are basic elements in this increase; they have provided
 a convenient source not only of raw materials to which
machinery has been applied with fruitful results, but as well
of the raw materials out of which the machines themselves
have been made and the fuel with which to run them. In
other words, our vast natural resources have been the basis
of our abundant supply of capital in the form of productive
equipment, which in turn has aided in bringing about the
rapid mechanization of industry. At the same time other
physical and political features—large population, the diversity
 of regional demands, and the absence of inter-regional
trade restrictions, such as tariffs—have furnished a domestic
market exceeding in magnitude and diversification that of any
other industrial nation. The magnitude of the market, the
abundance of capital, and the education of American consumers
 by persistent advertising to accept standardized
articles have encouraged the development of mass production,
 which in turn has permitted a reduction in unit costs.
The growth of large corporations, the resort to mass production,
 and the movement toward integration of industrial
operations in process in this country during recent years are
too familiar to require evidence. . . .
Large-scale production is especially economical where large
quantities of the same products can be produced. The magnitude
 of our domestic market and the willing acceptance of
standardized articles make feasible such repetitive processes.
Large-scale production is dependent upon the machine
process, and the increasing use of machinery and power and
labor-saving devices has accompanied the growth in size of
productive units. . . .
Power has been substituted for labor not only through machines
 of production but also in the form of automatic conveying
 and loading devices. In this connection contributions