Note: The term "immigrants" refers to people residing in the United States who were not US citizens at birth. This population includes naturalized citizens, legal permanent residents, certain legal non-immigrants (e.g., refugees and persons on student or work visas), and persons illegally residing in the United States.

Source: Data for 1850 to 1990, excluding 1940 and 1950 are from: Campbell J. Gibson and Emily Lennon, "Historical Census Statistics on the Foreign-born Population of the United States: 1850-1990" US Census Bureau, Population Division, Working Paper No. 29, February 1999. Data for 1940 and 1950 are from MPI analysis of decennial census data made available by Steven Ruggles, J. Trent Alexander, Katie Genadek, Ronald Goeken, Matthew B. Shroweder, and Matthew Sobek, Integrated Public Use Microdata Series: Version 5.0 [Machine-readable database]. Minneapolis: University of Minnesota, 2010. Data for 2000 are from MPI analysis of decennial census data; data for 2010 and 2011 are from MPI analysis of data from the US Census Bureau's 2010 and 2011 American Community Survey.