What would happen to the US if all blacks were to leave work?

As we know the backbone of industrial America is because of the black man, who were also did the bulk of the fighting against Japan in WW2. Why is it then that as soon as anything gets hard they always blame the BLACK and the immigrants who do all the work and always save the white population, with their innovation, hard work and model citizenship. I believe Obama now brings it to America how clear it is that black people are always persecuted just so that they can pay us less and you can always get more twiglets for your dollar.