When you say "black community", do you mean middle class black neighborhoods in the northeast, ghetto neighborhoods in any big city, dirt-poor sharecroppers in the deep south, middle-class south-central Los Angeles, inner city midwest, Texas cotton country? There are so many different sets of circumstances that could be called "a black community" in the US before the mid-50s as to make this question near impossible to answer, I would think.

How effective and widespread was blockbusting?