 By 1960, it grew to 813,000, fueled by the Second Great Migration of blacks into the city during World War II to work in the war industries and during the post-war economic expansion.The United States Supreme Court ruled in "Shelley v. Kraemer" in 1948 that racial covenant policies were unconstitutional, yet such practice continued without opposition over the next two decades.During the post-war economic boom, the Chicago Housing Authority (CHA) tried to ease the pressure in the overcrowded ghettos and put public housing sites in less congested areas in the city.