ect of Negro migration will show that these two types of forces or
causes were also present in this recent movement.

Again, these repellent or negative conditions which cause men to move
may arise in any of the various interests of human life, and may be
classified as economic, political, social, and religious. Of these
"the economic causes of migration are the earliest and by far the most
important. They arise in connection with man's effort to make his
living and concern all interests which are connected with his
productive efforts. They are disabilities or handicaps which affect
his pursuit of food, clothing and shelter, as well as the less
necessary comforts of life. These are vital interests and any
dissatisfaction connected with them is of great weight to men."

Inasmuch as the economic causes of migration are primal and most
important, and since like causes played such a large part in giving
rise to this recent movement, it might be well to pause here to
enumerate some of these causes, and to note briefly the nature of the
same. In the first place, a migration may occur because of permanent
infertility of the soil, harsh climate, or a dearth of natural
resources which may perpetually intensify man's struggle for
existence. In the next place, it may be due to temporary natural
calamities such as drought, famine, flood, extreme seasons and so on.
This latter set of causes, as will be seen later on, were prominent
factors in the recent Negro movement from the South to the
North. Again, people may be forced to move because of serious
underdevelopment of the industrial arts which may make living hard by
limiting the productive power of the people or by retarding them in
the struggle for trade. Finally, migration may be due to
overpopulation--a condition in which the population of a country has
increased to such a degree that there are too many people in
proportion to the supporting power of the environment.

As has just been intimated, the causes of migration are fourfold,
namely, economic, political, social, and religious. Because of this it
must not be thought, however, that these causes are separate and
distinct; but it should be understood that they overlap each other and
exist almost always in conjunction. In any migration two or more of
them will be found present. For example, it is very difficult to find
cases in which social causes alone account for a migration. They
often, nevertheless, act as a contribut