But blacks also migrated to escape the violence and social repression of Mississippi , where they had been essentially disenfranchised since 1890 and lived under Jim Crow laws .
Farm work declined with mechanization of agriculture .
Blacks also migrated to escape the violence and social repression of Mississippi , where they had been essentially disenfranchised since 1890 and lived under Jim Crow laws .
Farm work declined with mechanization of agriculture .