Compare the 1970 and 200 maps. What is changing about the ancestry of Americans? Where are most coming from? What observations can you make about different regions of the U. S.?

The racial and ethnic makeup of the American people is in flux. New immigrants from Asia and Latin America have added a large measure of cultural and phenotypic diversity to the American population in recent decades, just as waves of immigrants from Southern and Eastern Europe did a century ago (Bean and Stevens 2003; Higham 1988; Lieberson and Waters 1988: Ch. 2; Thompson and Whelpton 1933: Ch. 2). Moreover, the boundaries between racial and ethnic groups are becoming blurred by high rates of intermarriage and the growing number of persons with mixed ancestry (Lee and Bean 2004).

Answer is mass marketing.