"As of March 1997, according to data collected in the Current Population Survey, the estimated foreign-born population of the United States was 25.8 million- the largest in U.S. history. The number has climbed 6.0 million, or 30 percent, since the 1990 census, and 16.2 million, or 168 percent, since 1970, when the United States had the lowest number of foreign born in this century. The number of foreign-born U.S. residents now exceeds the population of all but 36 of the world's nations and each of our country's states, except California. Meanwhile, the proportion of the U.S. population that was foreign born reached an estimated 1 in 10 in 1997, the highest proportion since 1930. The 1997 figure is midway between the highest figures during a period of large-scale migration from Europe (14 percent in 1870 and 15 percent in 1890 and 1910) and the lowest figure during the culmination of a long period of limited migration (5 percent in 1970)."
Census Brief CENBR/00-2
Census Bureau: http://www.census.gov/