SEASONAL FLUCTUATIONS ol
ployment is diminishing; also the high level in November and
December corresponds with declining factory activity.
Coal Mining (Fig. B, Chart 54).
The low point in bituminous coal mining comes in the second
quarter of the year, at the period when immigration is greatest, and
the peak does not occur until some six months later; hence the
spring rush of immigrants is premature if their destination is the
bituminous coal mines.
The fluctuations in immigration are somewhat better timed for
anthracite coal mining, as the peak of activity in this industry is
reached after, rather than before, the high tide of arrivals. In both
types of mining, a decline occurs in November and December,
coincident with increasing emigration and declining immigration.
Selected Outdoor Industries (Fig. C, Chart 54).
The seasonal fluctuations in immigration are well timed for em-
ployment in the outdoor industries. The number of immigrants is
small in the stagnant months of December, January, and February,
increases with the spring rise in outdoor work, and reaches a peak
early enough to make it possible for the bulk of newly arrived im-
migrants to participate in outdoor work throughout the extent of
the summer boom. Then, as outdoor employment declines rapidly
in the closing months of the year, the tide of emigration swells
rapidly and the volume of immigration recedes.
All Selected Industries (Fig. D, Chart 54).
In general, the composite seasonal movement of employment in
all the selected industries exhibits the same features as the index
for outdoor industries, hence the comments just made for the outdoor
industries can be applied to the combined seasonal fluctuations in
employment in the entire group of industries under consideration.
The heaviest immigration is when employment is increasing and
somewhat in advance of the maximum in employment activity,
and the decline in immigration and the increase in emigration at the
close of the year coincides with the falling off of employment.
THE NET VOLUME OF ARRIVALS LESS DEPARTURES
AND THE MONTH-TO-MONTH CHANGES IN THE
NUMBER EMPLOYED
So far in this chapter we have been comparing the seasonal
changes in employment and pre-war migration with reference to
the time of year at which increases or decreases take place. There
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