... one of two equally deserving scientific projects but not both Passage 15 In the two decades between 19 10 and 19 30, over ten percent to the Black population of the United States left ... population had been located, and migrated to northern (5) states, with the largest number moving, it is claimed, between 19 16 and 19 18. It has been frequently assumed, but not proved, that ... cessation of European immigration caused by the outbreak of the First World War in 19 14. This assump- ( 15 ) tion has led to the conclusion that the migrants’ subse- quent lack of economic...