Unauthorized immigrants comprise slightly more than 4% of the adult population of the U.S., but because they are relatively young and have high birthrates, their children make up a much larger share of both the newborn population (8%) and the child population (7% of those younger than age 18) in this country.
These figures are based on data from the U.S. Census Bureau's March 2009 Current Population Survey, augmented with the Pew Hispanic Center's analysis of the demographic characteristics of the unauthorized immigrant population using a "residual estimation methodology" it has employed for the past five years.
The new Pew Hispanic analysis also finds that nearly four-in-five (79%) of the 5.1 million children (younger than age 18) of unauthorized immigrants were born in this country and therefore are U.S. citizens. In total, 4 million U.S.-born children of unauthorized immigrant parents resided in this country in 2009, alongside 1.1 million foreign-born children of unauthorized immigrant parents.
The report, "Unauthorized Immigrants and Their U.S.-Born Children" authored by Jeffrey S. Passel, Senior Demographer, Pew Hispanic Center, and Paul Taylor, Director, Pew Hispanic Center, is available HERE.