"Population declines exceeded 25 percent for the 1930s in some largely rural and agricultural counties of southwestern Kansas and the panhandle of Oklahoma...[while] California had sizable population growth... - US Census, County Population Change: 1930 to 1940"
Which conclusion can be drawn regarding the 1940 US Census information?
A) Population declined due to anxiety over the threat of World War II.
B) The conditions created by the Dust Bowl led to a westward migration.
C) The desire for wealth during the Gold Rush contributed to population growth.
D) Rural and agricultural counties lost population as a result of the completion of the Hoover Dam.