U.S. Federal: Documenting Origins of Apprehended Undocumented Persons

Discerning numbers of unauthorized or undocumented aliens residing within the borders of the United States is difficult. Census data can indicate the numbers of immigrants who were born elsewhere or those who allowed themselves to be enumerated by census takers. However, census numbers only count legal migrants and those voluntarily admitting to being in country without authorization. Determining actual numbers of illegal aliens necessitates going outside of the census numbers and finding other means of estimating populations. For example, studies conducted by The Pew Foundation provide an estimated number of 11,100,000 unauthorized immigrants present in the U.S. in 20142.