to
segregate and thus to classify the populations of great cities. In this
way the city acquires an organization which is neither designed nor
controlled.

Physical geography, natural advantages, and the means of transportation
determine in advance the general outlines of the urban plan. As the city
increases in population, the subtler influences of sympathy, rivalry,
and economic necessity tend to control the distribution of population.
Business and manufacturing seek advantageous locations and draw around
them a certain portion of the population. There spring up fashionable
residence quarters from which the poorer classes are excluded because of
the increased value of the land. Then there grow up slums which are
inhabited by great numbers of the poorer classes who are unable to
defend themselves from association with the derelict and vicious. In the
course of time every section and quarter of the city takes on something
of the character and qualities of its inhabitants. Each separate part of
the city is inevitably stained with the peculiar sentiments of its
population. The effect of this is to convert what was at first a mere
geographical expression into a neighborhood, that is to say, a locality
with sentiments, traditions, and a history of its own. Within this
neighborhood the continuity of the historical processes is somehow
maintained. The past imposes itself upon the present and the life of
every locality moves on with a certain momentum of its own, more or less
independent of the larger circle of life and interests about it.

In the city environment the neighborhood tends to lose much of the
significance which it possessed in simpler and more primitive forms of
society. The easy means of communication and of transportation, which
enables individuals to distribute their attention and to live at the
same time in several different worlds, tends to destroy the permanency
and intimacy of the neighborhood. Further than that, where individuals
of the same race or of the same vocation live together in segregated
groups, neighborhood sentiment tends to fuse together with racial
antagonisms and class interests.

In this way physical and sentimental distances reinforce each other, and
the influences of local distribution of the population participate with
the influences of class and race in the evolution of the social
organization. Every great city has its racial colonies, like the
Chinatowns of San Francisco and New Y