But the presence of any one of these features is a favoring condition for the development of the others.  Hence they are frequently found together, and of late this occurs increasingly.  It is difficult to say in every, indeed in any, case which feature has been cause and which effect in this development, but, on the whole, large production seems to have been primary.  Itself made possible by inventions, by better transportation, and by the widening of markets, it in turn helped to build up large individual fortunes, and then to create a need for the corporate form of organization.  And monopoly power no doubt is more easily gained by large aggregations of capital in a corporation having the advantages of large production.

Sec. 6. #Growth of large industry in the nineteenth century.# The great recent growth of the monopoly problem is in part to be explained as the result of the growth of large industry, not as the sole cause, but as a favoring condition.  Before the middle of the last century a tool-using household industry, on farms and in homes where the greater part of the things used were produced in the family, was still the typical organization in the United States.[6] A family produced somewhat more than it needed of food and cloth and exchanged with its neighbors; so with shoes, candles, soap, and cured meats.  The early factories growing out of the household industry were small.  Since that time two counter forces have been at work to affect the ratio of manufacturing establishments to population.  The number of small establishments has been increased by the many industries producing the things once made on farms, and by increasing demands for comforts and luxuries.  Many establishments producing the staple products that can be transported have been consolidated or have been enlarged, so that the unit of production now averages much larger.  The number of cotton-weaving factories was about the same in 1900 as it had been seventy years earlier, while population has grown six fold.  Iron-and steel-mills were fewer in 1900 than in 1880.  In industries having local markets or local sources of materials, such as grist mills and saw mills, the change in numbers was less, for many small establishments were started in outlying districts at the same time that the mills became larger in the great population centers.  But the average number of employees and the average capital per establishment increased in every period between census enumerations.

Sec. 7. #Methods of forming combinations.# Combinations of previously independent enterprises may be more or less complete and are made by different methods.  Four major methods are: 

(1) The pool, by which the enterprises continue to be separately operated, but divide the traffic (or output), or the earnings, or the territory, in prearranged proportions.

(2) The trust, in a legal sense (as defined above in section 5).

(3) The holding company, a corporation with the sole purpose of holding the shares of stock, or a controlling number of them, in various corporations otherwise nominally independent.