What are independent estimates of the unauthorized immigrant population in 2024 and how do they affect cost calculations?
Executive summary
Independent, academic and advocacy sources place the U.S. unauthorized immigrant population in divergent but overlapping ranges that matter enormously for any cost estimate: conservative residual-method counts cluster near 11–12 million for the early 2020s (DHS, MPI, CMS, Pew earlier figures), while more recent adjustments and alternative approaches have produced estimates as high as roughly 13.7–14.0 million for mid‑2023 — and incomplete data for 2024 leave the trend uncertain [1] [2] [3] [4] [5]. Because cost models for policies like mass deportation or large-scale detention scale roughly linearly with population totals and depend heavily on assumptions about who is counted (children, parolees, short‑term encounters), shifting the population estimate by a few million changes headline cost estimates by tens of billions of dollars [6] [7].
1. What the main independent estimates say — the headline numbers
Three widely cited, independent measures give different snapshots: DHS and residual‑method based work that informed many analysts put the unauthorized population around 10.9–11.0 million for 2022 (DHS, Pew earlier vintage, CMS/Passel) [1]; the Migration Policy Institute (MPI) using an updated residual‑imputation approach reported roughly 11.3 million in mid‑2022 and has produced state and county profiles suggesting a U.S. total in the low‑teens, with some public MPI materials referencing about 13.7 million for later snapshots tied to 2023 ACS pooling [2] [4]. Separately, Pew’s later reporting incorporated new Census adjustments and reported a 14.0 million estimate for 2023 in its updated materials [5] [8]. The Center for Migration Studies produced a provisional 11.7 million for July 2023 based on CPS methods, demonstrating method‑to‑method variance [3].
2. Why these independent estimates diverge — methodology and scope
Differences flow from three methodological choices: which survey or administrative data are used (ACS vs. CPS vs. administrative encounter tallies), how legal status is imputed or modeled (residual estimation versus alternative flow‑based methods), and whether recently paroled groups and repeat encounters at the border are treated as part of the resident unauthorized population [1] [2] [9]. Analysts using residual methods subtract estimated legally resident foreign‑born from total immigrant counts in surveys and thus are sensitive to undercounts and survey weighting decisions [1]. Flow‑oriented or alternative approaches that count arrivals or factor in different outflow assumptions can produce substantially larger totals [1].
3. What happened in 2023–24 and the limits on 2024 estimates
Record border encounters in 2023 complicated interpretation: a surge in encounters does not automatically equal a one‑for‑one rise in the resident unauthorized population because many encounters reflect short‑term releases, repeat crossings, expulsions, or later regularizations; MPI and other analysts warn that 2023–24 administrative activity may have slowed growth in the resident unauthorized population by late‑2024 even if encounters spiked earlier [2] [9]. Census Bureau updates to international migration estimates in December 2024 prompted revisions and undergirded Pew’s subsequent 2023 uptick, but both Pew and other groups stress that 2024 is only partially observed and that monthly CPS and administrative signals suggest growth slowed in the latter half of 2024 [5] [10].
4. How population uncertainty alters cost calculations
Cost estimates for policies such as mass deportation or large‑scale detention are highly sensitive to the population base and inclusion rules: Robert Shapiro’s May 2024 calculation used an 11‑million baseline to estimate roughly $265 billion to deport that many people — explicitly noting exclusions (American children, detention‑camp buildout) that would raise costs further — while the American Immigration Council’s scenario work put mass‑deportation costs at least $315 billion under different assumptions [6] [7]. If the unauthorized population is nearer 14 million, a straight proportional scaling of Shapiro’s figure would raise the arithmetic cost by roughly 27% (tens of billions), and additional line items (family separation, legal processing, detention infrastructure, welfare of U.S.‑born children) compound non‑linear cost drivers that make simple per‑person multipliers conservative lower bounds [6] [7].
5. Policy implications and the case for careful modeling
Because independent estimates vary and 2024 data remain incomplete, any policy costing exercise must be explicit about the population baseline, treatment of parolees and children, and assumed outflows (returns, legalizations, deaths) — variables that each carry empirical uncertainty and political stakes [1] [2]. Advocacy organizations and think tanks produce divergent headline figures in part because their scenarios differ in scope and intent; transparent sensitivity analyses that show cost ranges under 11M, 12M, and 14M baselines are the only defensible way to present fiscal impacts given the available independent estimates [6] [7].
6. Bottom line
Independent estimates for 2024 are not uniform: residual‑based counts cluster near 11–12 million, Census adjustments and some MPI/Pew interpretations push the 2023 snapshot toward roughly 13.7–14.0 million, and 2024 trends are only partially observed such that cost projections must present ranges and clear assumptions; shifting the baseline by a few million changes mass‑action cost estimates by tens of billions and often more once secondary impacts are included [1] [2] [5] [6] [7].