An immigrant or foreign-born person is someone born outside the US and its territories. People born in the US, Puerto Rico, and other territories, or born abroad to US citizen parents, are native born.

Children of immigrants have at least one foreign-born parent.

Immigrants include both legal and unauthorized immigrants, though unauthorized immigrants are somewhat undercounted in the official Census and ACS data.

Children of Immigrants: National and State Characteristics, Urban Institute tabulations from the Integrated Public Use Microdata Series dataset from the 1990 U.S. Census of Population and Housing and the 2005 and 2006 U.S. Census Bureau American Community Surveys (ACS), August 2009. Available at: http://www.urban.org/publications/411939.html.