Until the 1960s many historians believed that ethnic group influence on foreign policy would gradually diminish as the population became an American population with fewer immediate ethnic ties. Beginning in the 1920s, the flow of immigration slowed dramatically with laws reflecting anti-immigration public sentiment. Depression and war continued the trend to the point where under 5 percent of the population had been born in a foreign country. The political and cultural trends that lasted through the 1950s stressed the need for assimilation and conformity to the mainstream norms. The Cold War, with its emphasis on the righteousness of the American position and its constant invocation of national patriotism, further inhibited criticism of mainstream American values and institutions. School textbooks extolled the virtues of the "melting pot" to which other cultures contributed, but nonetheless stressed the importance of unity and adaptation to the national norm.
As with so much else in national life, these concepts and the national ethnic and racial makeup changed dramatically in the 1960s. An event that unmistakably precipitated the changes, and one whose legacy might well include significantly altering the policies of American diplomacy in the decades ahead, is the Immigration Act of 1965. Sponsored by liberal Democrats in Congress and Presidents John Kennedy and Lyndon Johnson, this law changed the rules of entering, and thereby opened the doors to the greatest influx of immigrants in history. The Hart-Celler Act, as it was then known, received little attention when it was passed, and continues to be relatively ignored in histories recounting Johnson's reform program, the Great Society. Nonetheless, it may be the single most significant legislation of that era as far as its impact on the nation's future.
Rejecting national origin quotas as the basis for admittance, as had previously been the case, in the 1965 law family reunification became the basis for admittance for nearly two-thirds of those who would immigrate. Three subsequent laws increased the impact of the 1965 law: the Refugee Act of 1980, which recognized a separate category of those fleeing political oppression; the Immigration and Control Act of l986, which provided amnesty for three million immigrants who had entered the United States illegally before l982; and a 1990 amendment to the l965 law that substantially raised the number who could enter as legal immigrants.
The flow of immigrants has risen steadily, particularly after 1990, when the annual totals for legal immigration peaked for several years at approximately 1.5 million. Between 1965 and 2000, approximately 23 million immigrants legally entered the United States. Adding estimates that there are also from 8 to 12 million illegal immigrants, the total attests to a massive foreign-born influence. Twenty-five percent of California's population is foreign born, and New York state is not far behind, with about 20 percent.
As important as the sheer number of immigrants is, it is also significant that 85 percent of the legal immigrants are from non-European backgrounds without the traditional foreign policy interests of most Americans. Europeans comprise approximately 15 percent of legal immigrants, Asian Americans about one-third, and Latin Americans most of the rest. The foreign policy issues that concern these new Americans have already begun to shape the direction of diplomacy, notably on trade and on immigration issues, such as amnesty for undocumented workers already in the country. Future diplomacy is likely to concern such issues more directly. One reason is that demographers project that, because of higher Hispanic birthrates and the origins of future immigrants, the United States will see a decline in its population of European background and a substantial rise in its Hispanic and Asian population.