The city

by Robert Ezra Park; E. W. Burgess; Roderick Duncan McKenzie

III. DETERMINING ECOLOGICAL FACTORS IN THE GROWTH OR DECLINE OF COMMUNITY

The human community tends to develop in cyclic fashion. Under a given state of natural resources and in a given condition of the arts the community tends to increase in size and structure until it reaches the point of population adjustment to the economic base. In an agricultural community, under present conditions of production and transportation, the point of maximum population seldom exceeds 5,000.[^[40]] The point of maximum development may be termed the point of culmination or climax, to use the term of the plant ecologist.[^[41]] The community tends to remain in this condition of balance between population and resources until some new element enters to disturb the status quo, such as the introduction of a new system of communication, a new type of industry, or a different form of utilization of the existing economic base. Whatever the innovation may be that disturbs the equilibrium of the community, there is a tendency toward a new cycle of adjustment. This may act in either a positive or negative manner. It may serve as a release to the community, making for another cycle of growth and differentiation, or it may have a retractive influence, necessitating emigration and readjustment to a more circumscribed base.

In earlier conditions of life, population was kept down to the community balance by variations in the death-rate, or, as in the case of Greek cities, the surplus population emigrated in groups to establish new colonies—offshoots of the mother-city. Under modern conditions of communication and transportation, population adjustment is maintained by a ceaseless process of individual migrations. As a result of the dynamic conditions prevailing throughout the civilized world during the last fifty years, many communities have passed through swift successive cycles of growth or decline, the determining factors being changes in forms and routes of transportation and communication and the rise of new industries.

Some advantage in transportation is the most fundamental and most important of the causes determining the location of a distributing center. It may almost be said to be the only cause for the formation of such centers. For some reason or reasons a particular place is more conveniently and cheaply reached by many people than any surrounding point; and, as a result, they naturally exchange commodities there. The country store is located at the crossing of roads. There also is the village. In a mountain country the market town is at the junction of two, or, still better, of three valleys. Another favorite location is the end of a mountain pass, or a gap that is a thoroughfare between two valleys. If rivers are difficult to cross, settlements will spring up at the safest ferries or fords. In a level plain, a town will be near its center, and a focus of roads or railroads in such a plain, fertile and populous, will almost surely make a city.[^[42]]

It is the railroad and the steamship that determine where a new business shall be developed, quite as often as the government policy. The grant of special rates and privileges to shippers is nowadays the most efficient kind of protection.

It is this quickening and cheapening of transportation that has given such stimulus in the present day to the growth of large cities. It enables them to draw cheap food from a far larger territory and it causes business to locate where the widest business connection is to be had, rather than where the goods or raw materials are most easily produced. And the perfection of the means of communication, the post-office and the telegraph, intensifies the same result.[^[43]]

The entire net increase of the population of 1870 to 1890 in Illinois, Wisconsin, Iowa, and Minnesota was in cities and towns possessing competitive rates, while those having non-competitive rates decreased in population, and in Iowa it is the general belief that the absence of large cities is due to the earlier policy of the railways giving Chicago discriminating rates.[^[44]]

The advent of the trolley line and more recently of the automobile has produced still further disturbing elements in the growth of human communities. Their effect has been chiefly to modify the life of the small town or village, causing the decline of some and the sudden growth of others. The introduction of these two forms of transportation, more particularly of the automobile, has been the most potent force in our recent American history in affecting redistribution of our population and in the disorganization of our rural and small-town institutions which grew up on the basis of a horse-and-vehicle type of mobility.[^[45]]

The evolution of new types of industry is another feature that becomes a determining factor in the redistribution of the country’s population. As we review our census reports we see the emergence each decade of one or more important industries; first, the textile industry causing concentrations of population in the eastern states, then the development of the iron and steel industry with its center of operations gradually shifting farther and farther west, and more recently the advent of the automobile and oil industries making for enormous concentration of population in certain states of the Union, also the motion picture industry with its concentrated center in southern California. The emergence of a new industry has a far-reaching effect in disturbing the status quo of communal life. Competition soon forces the new industry to concentrate its productive enterprises in one or two communities; these communities then serve as great magnets drawing to themselves the appropriate population elements from communities far and near.