Measuring the Foreign-born Population in the United States with the Current Population Survey: 1994-2002 [open pdf - 1MB]
"The estimated size of the foreign-born population of the United States in 2002 was 32.5 million based on data collected in the Current Population Survey (CPS)- Annual Social and Economic Supplement (ASEC). In absolute terms, this estimate represented an increase of 64.2 percent or 12.7 million over the estimated 19.8 million in the 1990 census, the largest foreign-born population living in the United States since record-keeping began in 1850. The challenge of monitoring the welfare of this newly arrived and large foreign-born population has created a demand for statistical information. Until 1994, when nativity items were added to the CPS, the decennial census was the sole source of regularly collected information about this group. While census data remain a primary source of information about the foreign born for subnational governmental jurisdictions and other small areas, census data are collected only once every ten years and quickly become outdated. In recent years, the American Community Survey (ACS) has become a new source of information. ACS data are collected monthly and tabulated annually, and have been designed to update and eventually replace decennial census sample data. The relatively larger ACS sample yields more precise estimates than the CPS, for both subnational geographic areas and foreign-born population subgroups. Over the past three years, the Census Bureau has been developing and testing a citizenship question for inclusion in the Survey of Income and Program Participation (SIPP) core questionnaire."
Population Division Working Paper #73
Census Bureau: http://www.census.gov/