How do DHS 'encounters' differ from estimates of the unauthorized immigrant population?
Executive summary
DHS “encounters” are operational counts of interactions between migrants and U.S. authorities—events recorded in enforcement tables—not measurements of the resident unauthorized population [1] [2]. By contrast, estimates of the unauthorized immigrant population are statistical constructs produced by demographers using survey data and administrative records—typically the residual method applied to Census Bureau surveys plus corrections for undercount and legal admissions [3] [4]. Conflating encounters with population change ignores repeat interceptions, rapid returns, legal admissions, emigration and methodological adjustments that researchers explicitly account for [5] [6].
1. What DHS "encounters" measure and why they spike in public view
DHS publishes monthly operational tables showing encounters—records of apprehensions, referrals and other contacts at ports of entry, the border and in the interior—which are useful for tracking enforcement workload and border activity but are event tallies, not head counts of unique residents [1] [2]. Those encounter totals can surge quickly when migration flows intensify or enforcement posture changes, and DHS and other agencies report encounters alongside detentions, removals and returns as part of enforcement statistics [1] [7].
2. How demographers estimate the unauthorized resident population
Independent researchers and agencies use the “residual” method: start with survey-based estimates of the total foreign-born population from the American Community Survey or CPS, subtract the legally resident foreign-born identified through administrative records (green cards, visas, refugee grants), and adjust for deaths, emigration and survey undercount to produce an estimate of unauthorized residents [3] [4]. Multiple institutions—DHS OHSS, Pew, MPI and CMS—use variants of this approach and historically produce estimates in a similar range, for example roughly 11.0 million for 2022 in several analyses [3] [8] [4].
3. Why encounters can far exceed population growth: the arithmetic of events versus stocks
Encounters record events; population estimates measure the stock of people living in the country. Over time, millions of encounters can occur without increasing the resident unauthorized population by the same amount because many intercepted migrants are quickly returned or removed, some are intercepted multiple times, and some later obtain lawful status or emigrate—processes that residual methods and administrative tallies explicitly treat as offsets [6] [5]. Historical comparisons show far more cumulative apprehensions than net population growth—for example, one analysis noted 33.7 million apprehensions versus a 6.8 million population increase over three decades—illustrating that apprehensions are not a 1:1 proxy for resident population change [6].
4. The “gotaways,” court processes and temporary stays complicate simple math
Some migrants encountered at the border are not admitted and are returned; others are issued notices to appear and remain in the United States while their cases proceed for months or years—meaning short-term presence, court backlogs and eventual outcomes all affect whether an encounter translates into a new resident counted in population estimates [9] [1]. Analytical teams warn that media or social-media tallies that simply add encounters to prior population estimates commit the same mistake made in earlier eras—treating attempted entries and repeated interceptions as net growth without accounting for rapid returns or removals [5] [6].
5. What this means for policy debates and public understanding
Policymakers and the public need both types of data: encounters illuminate operational pressure points at the border and the demand for enforcement resources, while residual population estimates inform long-term demographic, economic and social policy planning [1] [3]. Misreading encounters as direct measures of resident population inflates perceptions of short-term population change and can drive misleading claims; major research groups and DHS caution against that leap and provide methodological explanations to prevent it [5] [4].
6. Limitations, competing estimates and open questions
Residual estimates depend on survey coverage, assumptions about undercount and emigration, and timely incorporation of administrative changes; DHS, Pew, MPI and CMS sometimes diverge modestly because of methodological choices and updated source data, and some recent high-tempo migration periods post-mid-2022 have challenged real-time estimation [3] [10] [11]. Sources note that DHS administrative data are rich but have not been fully leveraged to produce precise emigration estimates for external researchers, leaving some uncertainty in translating high encounter volumes into net population change [10].