Every year, the Department of Homeland Security (DHS) is required to submit a report to Congress on trends in immigration and naturalization, including how many people are unlawfully present in the United States.
DHS’s report of December 2018 estimated 11.96 million foreign-born individuals were unlawfully residing here as of January 1, 2015.
The Government Accountability Office (GAO) recently reviewed DHS’s March 2019 report which listed various approaches that could improve its annual estimates, such as using more precise mortality estimates for foreign-born populations rather than standard demographic tables.
In its report published September 10, GAO noted that DHS has identified various limitations to its estimates of the unlawfully resident foreign-born population in the United States, and eight possible approaches the department or other entities could take to improve the estimates.
DHS officials and stakeholders identified the limitations that most significantly impact DHS’s estimates to be uncertainty regarding the size of the American Community Survey undercount (nonrespondants), which affects the estimate of the total foreign-born population, and uncertainty regarding emigration rates of foreign nationals, which affects the estimate of the legally resident foreign-born population. DHS also reported limitations related to foreign national mortality data, which also affect the estimates of the legally resident foreign-born population, and other limitations.
In its March 2019 report, Potential Improvements to DHS Illegal Alien Population Estimates: Collection and Use of Data, DHS identified possible approaches to improve its estimates of the unlawfully resident population. Some approaches address limitations DHS and stakeholders identified as the most significant, and others aim to improve DHS data systems to strengthen DHS’s population estimates and improve its overall immigration reporting and analysis.
GAO found that DHS has ongoing work that should help implement three of the eight approaches:
Collect additional information about foreign-born departures. DHS has ongoing efforts to implement a system to collect information on departures of foreign-born individuals through land ports of entry. Officials told GAO that once the program is completed, they plan to use data from land ports of entry to enhance their estimates.
Implement the Immigration Data Integration Initiative (IDII). Officials stated that DHS is making progress implementing its IDII—which involves copying and linking together data from multiple immigration data systems to a single environment—and they expect to use IDII data soon.
Capture additional immigration data electronically. DHS has work underway to collect more data electronically when processing immigration benefits, which may be able to provide more descriptive data about the foreign-born population.
To implement the other five approaches, DHS proposes potentially coordinating with outside entities such as the U.S. Census Bureau or a private entity that would conduct relevant research. The remaining approaches are:
- Assess the size of the undercount of foreign-born populations in the U.S. Census American Community Survey
- Develop nativity-specific mortality estimates
- Assign unique identifiers to nonimmigrants
- Launch a new version of the New Immigrant Survey
- Include questions about lawful permanent resident status adjustments in the Census Survey of Income and Program Participation
