The United States has been a nation of immigrants for much of its history. Although it has not always extended the ready welcome implied by the famous Emma Lazarus poem, it has nonetheless long been the leading host country for the world's migrants. At the turn of the last century, this country absorbed unprecedented numbers of newcomers. Today, at the dawn of a new millennium, the United States is experiencing yet another great wave of immigration. More than 25 million immigrants have entered the country since the 1960s (Jones-Correa 2002). The current immigration flow is, in fact, historically unprecedented, both for its numerical proportions and for its demographic composition.

First, the number of newcomers to the United States in the last four decades has exceeded the high-water mark achieved during the last great wave of migration to this country from 1880 to 1920. With this latest influx of immigrants, there are now over 35 million foreign-born people living in the United States, that is, more than 10 percent of the total population. The proportions are even more substantial in cities around the country. Thirteen of the nation's cities house more than half of the immigrant population. For instance, roughly one of every three New Yorkers is a person of foreign birth (Logan 2003). Immigrants constitute even greater shares of the population in Los Angeles and Miami (ibid.). Their proportions are expected to continue inching upward, as the current immigration trends show no signs of abating.