GMAT阅读 ——（3）

? In the two decades between 1910 and 1930, over
ten percent to the Black population of the United States
left the South, where the preponderance of the Black
population had been located, and migrated to northern
(5) states, with the largest number moving, it is claimed,
between 1916 and 1918. It has been frequently assumed,
but not proved, that the majority of the migrants in
what has come to be called the Great Migration came
from rural areas and were motivated by two concurrent
(10) factors: the collapse of the cotton industry following
the boll weevil infestation, which began in 1898, and
increased demand in the North for labor following
the cessation of European immigration caused by the
outbreak of the First World War in 1914. This assump-
(15) tion has led to the conclusion that the migrants’ subse-
quent lack of economic mobility in the North is tied to
rural background, a background that implies unfamil-??
iarity with urban living and a lack of industrial skills.
? But the question of who actually left the South has
(20) never been rigorously investigated. Although numerous
? investigations document an exodus from rural southern
areas to southern cities prior to the Great Migration.
no one has considered whether the same migrants then
moved on to northern cities. In 1910 over 600,000
(25) Black workers, or ten percent of the Black work force,
reported themselves to be engaged in “manufacturing
and mechanical pursuits,” the federal census category
roughly encompassing the entire industrial sector. The
Great Migration could easily have been made up entirely
(30) of this group and their families. It is perhaps surprising?
to argue that an employed population could be enticed
to move, but an explanation lies in the labor conditions
then prevalent in the South.
About thirty-five percent of the urban Black popu-