MIGRATION AND BUSINESS CYCLES 
changes in the level of prices, there is a relative labor shortage when 
employers are unable to hire laborers at wages which have been 
customary; and likewise a labor surplus when workmen, able and 
willing, are unable to find employment at what has been the pre- 
vailing wage. 
This monograph is devoted primarily to consideration of these 
short-period aspects of the relation of migration to labor supply, in 
an effort to determine whether migration tends to intensify or to 
minimize the intensity of the business cycle and particularly whether 
that phase of the business cycle most directly and obviously inimical 
to human welfare—the unemployment phase—is rendered more or 
less severe in its effects because of migratory movements. 
The Questions for Solution. 
The objects of our inquiry may be conveniently summarized in 
the following questions to which answers are sought in the analysis 
set forth in the subsequent chapters: 
1. To what extent do cyclical and seasonal fluctuations in 
migration correspond, in time and degree, with fluctuations 
in industrial activity, particularly as measured by employ- 
ment or unemployment? 
: What noteworthy variations in cyclical and seasonal fluctua- 
tions appear when migrants are classified by sex, prior oc- 
cupation, race, or country of origin? 
» What is the relative influence of the “push” or the “pull” 
upon fluctuations in migration; that is, are such fluctuations 
primarily determined by changes in the country of emigration 
or in the country of immigration? 
What is the economic significance of the ascertained ten- 
dencies? 
The Conflicting Interpretations. 
A scrutiny of the scientific and popular literature of immigration 
reveals diverse interpretations of the effect of migration upon the 
fluctuations in employment which may, for the sake of brevity, be 
designated as the “safety-valve’”’ and the “maladjustment” theories 
of migration. 
Those who advance the safety-valve theory look optimistically 
upon the effect of immigration and urge that the coming and going 
of the alien immigrant and the alien emigrant are so timed that 
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