Between 1790 and 1920 the population of the United States grew from 4 million to 106 million. About 1 million new immigrants —most of them European—had arrived each year, and by the 1920 census, the foreign-born comprised more than 13 percent of the U.S. population. Responding to public anxieties about this large influx of newcomers, Congress passed the Quota Act in 1921, which set a cap of 360,000 new immigrants per year. This act also established a nationalorigins preference that favoured immigrants from England, Scandinavia, Germany, and France over those from southern Europe, Asia, and Africa. Coupled with the impact of the Depression and World War II, these regulations dramatically reduced immigration to the United States. Between 1930 and 1950 only 4 million newcomers became American citizens— less than half the number of immigrants that had arrived during the first decade of the twentieth century.

In the 1960s significant policy revisions again changed the makeup and number of immigrants coming to the United States. Prompted by the successes of the civil rights movement, Congress chose to end racially restrictive immigration quotas by passing the Immigration and Nationality Act of 1965. This act, which took effect in 1968, set an annual immigration cap of 290,000—170,000 from the Eastern Hemisphere and 120,000 from the Western Hemisphere. In addition, this new law established a “family preference” rule, which granted favour to the close relatives of immigrants already living in the United States. In effect, relatives of immigrants who were U.S. citizens were exempt from the quota system. During the mid-1960s, Latin American and Asian countries still had a relatively low proportion of visas available to immigrants, but due to the family preference system, it was not long before these countries contributed a substantial portion of America’s new immigrants. By 1990, 44 percent of America’s legal immigrants were from Latin America and the Caribbean, and 36 percent came from Asia. Less than 15 percent were from Europe.

The new quota system and family preference policy were not the only factors affecting the numbers and demographics of U.S. immigrants. Illegal immigration of migrant workers increased dramatically after the 1965 Immigration Act cancelled the Bracero program, which since the 1940s had allowed foreigners—mostly Mexicans—to take temporary agricultural jobs in California and Texas. In one of its first serious attempts to control illegal immigration, Congress passed the Immigration Reform and Control Act (IRCA) in 1986. The act had two parts: It provided amnesty to illegal immigrants who could prove they met certain requirements for living and working in the United States, and it sanctioned employers for hiring undocumented workers. Most analysts agree, however, that the IRCA had little effect in reducing illegal immigration. According to the U.S. Immigration and Naturalization Service, about 200,000 to 300,000 illegal immigrants enter the United States annually.

Not only did restrictions on illegal immigration fail to significantly reduce the total number of immigrants entering the country, but new policies led to overall increases. Higher immigration caps that took effect in 1990 now allow 700,000 to one million legal immigrants into America each year. Out of a current total U.S. population of 284 million, immigrants comprise 10 percent of American residents— 28.4 million. By the year 2050 the U.S. population is projected to increase to 400 million, with immigrants contributing to two-thirds of that growth.

For many Americans, such a large number of newcomers —and the prospect of millions more—is unsettling. Some experts are concerned that the accelerated population growth resulting from immigration could overtax the country’s municipal, natural, and economic resources. Sociologist Christopher Jencks, for example, maintains that cities will become grossly overcrowded, resulting in gridlocked