Jeffrey S. Passel

The flow of immigrants from Mexico to the United States has declined sharply since mid-decade, but there is no evidence of an increase during this period in the number of Mexican-born migrants returning home from the U.S.

Hispanics now make up 22% of all children under the age of 18 in the United States--up from 9% in 1980--and as their numbers have grown, their demographic profile has changed.

The question of who's Hispanic -- and who isn't -- turns out to be pretty complicated.

There were 11.9 million unauthorized immigrants living in the United States in March 2008. The size of the unauthorized population appears to have declined since 2007.

If current trends continue, immigrants arriving from 2005 to 2050 and their descendants will account for 82% of the population growth in the United States during this period, according to new projections from the Pew Research Center.

If current trends continue, the population of the United States will rise to 438 million in 2050, from 296 million in 2005, and 82% of the increase will be due to immigrants arriving from 2005 to 2050 and their U.S.-born descendants.

The proportion of all legal foreign-born residents who have become naturalized U.S. citizens rose to 52% in 2005, the highest level in a quarter of a century and a 15 percentage point increase since 1990.

Analysis of the March 2005 Current Population Survey shows that there were 11.1 million unauthorized migrants in the United States a year ago.

Hispanics accounted for half of the population growth in the United States between the elections of 2000 and 2004 but only one-tenth of the increase in the total votes cast.

Most of the unauthorized population lives in families, a quarter has at least some college education and illegal workers can be found in many sectors of the US economy.