PIP: This article provides a historical perspective on immigration policy in the US after World War II and assesses the present situation. US immigration and refugee policy has undergone significant change since World War II. The McCarran-Walter Act of 1952, which instituted a system of proportional quotas based on national origins, was discarded in 1965 following years of criticism that it discriminated against nonwhites. Third World immigrants, especially from Asia and the Americas, have benefited from the immigration laws. However, the problems resulting from unrestricted and undifferentiated immigration are now becoming apparent, even to liberal critics of previous national origins policies. During the 1970s, there was a 61% increase in the number of Mexican nationals in the US and Mexicans currently comprise over 20% of the population in 40 Congressional districts in 8 states. 83.3% of legal immigrants, and all illegal immigrants, are of non-European descent--a fact that may retard their assimilation and intensify ethnic tensions. There is a danger that the concept of national borders may become superfluous. The theoreticval liberalism of the 1950s and 1960s is, in the 1970s, being confronted with the reality of large numbers of immigrants unable and unwilling to be absorbed into a previously European-dominated country. It is concluded that the enforced application of the concept of equality in matters of immigration has not been the panacea that its liberal proponents envisioned.