“[O]ur cities will not be flooded with a million immigrants annually. Under the proposed bill, the present level of immigration remains substantially the same. . . . Secondly, the ethnic mix of this country will not be upset. . . . Contrary to the charges in some quarters, S. 500 will not inundate America with immigrants from any other country or area, or the most populated and economically deprived nations of Africa and Asia. . . .”