http://en.wikipedia.org/wiki/Blockbusting
The term “blockbusting” might have originated in Chicago, Illinois, where, in order to accelerate the emigration of economically successful racial, ethnic, and religious minority residents to better neighborhoods beyond the ghettos, real estate companies and building developers used agents provocateurs — non-white people hired to deceive the white residents of a legally-restricted neighborhood into believing that black people were moving into the neighborhood, thereby encouraging them to quickly sell (at a loss) and emigrate to racially-restricted suburbs.
The tactics included hiring black women to be seen pushing baby carriages in white neighborhoods, so encouraging white fear of devalued property; selling a house to a black family in a white neighborhood to provoke white flight, before the community’s properties became worthless; selling white neighborhood houses to black families, and afterwards placing real estate agent business cards in the neighbors’ mailboxes; and saturating the neighborhood area with fliers offering quick-cash for houses. Like-wise, building developers bought houses and dwelling buildings, and left them unoccupied to make the neighborhood appear abandoned — like a ghetto or a slum — psychologic coercion that usually forced the remaining white folk to sell at a loss. Blockbusting was a very common and very profitable form of racist exploitation, for example, by 1962, when blockbusting had been practiced for some fifteen years, the city of Chicago had more than 100 real estate companies that had been, on average, “changing” between two to three blocks a week for years.