science research can make to policy debates and to identify gaps in current understanding.
Assessments of the social consequences of immigration often arouse strong reactions. Some critics of contemporary immigration policy conclude that the arrival of predominantly nonwhite immigrants displaces native workers, swells the largely minority ''underclass," and exacerbates racial and ethnic conflict (Brimelow, 1995; Bouvier, 1991; Lamm and Imhoff, 1985). Others conclude that the new immigrants strengthen and reinforce the best in American traditions, revitalize decaying neighborhoods and stagnant industries, and add new talents and energies to the U.S. civic culture (Binder and Reimers, 1995; Simon, 1989; Portes and Rumbaut, 1996).
Contemporary reactions have historical parallels. Before the enactment of restrictions on immigration in the 1920s, intense debates erupted over whether the new immigrants from Eastern and Southern Europe could ever be assimilated.2 Contemporary fears about the social consequences of immigration are typically expressed in less graphic language than those in the past, but the sentiments are not dissimilar.
Although it is not possible to resolve all controversies over the impact of immigration, enough is known to allay some of the widely held concerns that immigration has exacerbated the social problems that confront American society in the late twentieth century. Over time, many immigrants, and especially their children, have become integrated into the mainstream of American society (Alba, 1995; Hirschman, 1983; Lieberson, 1980; Portes and Rumbaut, 1996), and immigrants have made significant contributions to many American institutions. It is also true that some immigrants have participated in crime, and interethnic tensions and violence, sometimes directed at other immigrants, have surfaced. But the weight of both the historical and the current evidence is that immigrants are no more likely to participate in socially disapproved activities than are native-born Americans. Although there is no assurance that past trends will always continue, the new Americans who have arrived in recent decades are likely to also be absorbed into the primary institutions of American society. As with many past waves of immigrants, they will also redefine the character and content of American culture in the process.
At the beginning of the twentieth century, many scholars believed that Southern and Central European "races" were genetically inferior to the Northern and Western European groups who had emigrated to the United States in earlier times and had defined American culture (Ross, 1914; Grant, 1916; for a masterly review of American nativism, see Higham, 1955). For example, in a full page ad in the Sunday New York Times on June 22, 1913, William Ripley, a Harvard economics professor, wrote that "the hordes of new immigrants" were "a menace to our Anglo Saxon civilization." Another economist, Robert Foerster, toured Latin America to investigate the effects of immigration from the rest of the Western Hemisphere for the U.S. Department of Labor. "He concluded, in a report published by the government in 1925, that broad entry by Latin Americans would 'lower the average of the race value of the white population of the United States"' (Muller, 1993:41).