The suburbs of the metropolitan areas exhibit very different population trends. Negroes made up only 4 per cent of their population in 1940 and less than 5 per cent in 1950. The pattern of Negro population growth within the central cities follows established and well-understood patterns. It is based upon immigration from the South, and it is accelerated by a larger rate of natural increase of the nonwhite in-migration in comparison with the older white residents. The racial attribute—skin color—is added to the social attributes of lower class behavior. And while Negroes, like other urban immigrants can readily lose undesirable social attributes, they cannot lose their color. The total political picture of continued racial bifurcation forecasts a new round of political repression aimed at Negroes. For this one, they will be better armed—effective numbers, economic strength, political sophistication, and allies in the white population.