The current wave of immigration, which rivals the massive influx of 1880-1914, started with the Immigration and Nationality Act of 1965. Since then, about 27 million legal immigrants have crossed the border. In addition, an estimated 10.3 million illegal ones live in the U.S. The net result is that, as of 2004, there were 34.2 million foreign-born residents in the country. More than half are from Latin America and about a quarter from Asia, which contrasts with the pre-World War I period, when the foreign-born were overwhelmingly European.

Today's surge, like its predecessor, is profoundly affecting the culture and economics of the U.S., particularly in southern Florida, southern California and the New York metropolitan area. In 2004 the foreign-born accounted for 11.3 percent of the population, and at their present rate of increase, this figure could exceed the record of 14.6 percent in 1890. The foreign-born now account for half the growth of the U.S. population.