Data sources for this report include the 1990 census, the 1995 and 2000 Current Population Survey, and the 2005-2015 American Community Survey, all from the U.S. Census Bureau. Data are adjusted and augmented for undercount. For details, see methodology of the Pew Research Center report “Overall Number of U.S. Unauthorized Immigrants Holds Steady Since 2009.”

Data for the immigrant population from all countries and from Central American countries, as well as immigrant inflows to the U.S., are rounded to the nearest 5,000 for populations under 1 million, the nearest 10,000 for populations between one and 10 million, and to the nearest 25,000 for populations over 10 million. Estimates for unauthorized immigrant populations are rounded differently, according to the rounding rules in the Pew Research Center report “Overall Number of U.S. Unauthorized Immigrants Holds Steady Since 2009.”

The 2011 National Survey of Latinos was conducted from Nov. 9 through Dec. 7, 2011. Results are based on telephone interviews conducted by Social Science Research Solutions (SSRS), an independent research company, among a nationally representative sample of 1,220 Latino respondents ages 18 and older. Of these, 492 respondents were U.S. born (including Puerto Rico) and 728 were foreign born (excluding Puerto Rico). Of the foreign born, 299 were U.S. citizens, 261 were legal residents and 140 were not citizens and not legal residents.

The Encuesta de Migración en la Frontera Sur (EMIF-Sur) has been conducted since 2004, although only 2016 data were included in this report. The surveys of deportees are conducted among a representative sample of people deported from the United States and Mexico in four cities and in the main airports of the three Northern Triangle nations (El Salvador, Guatemala and Honduras).