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What is the estimated illegal immigrants number in the united states
Executive summary
Estimates of how many unauthorized or “illegal” immigrants live in the United States vary widely: leading academic and nonpartisan estimates put the mid‑2023 figure between about 13.7 million and 14 million (MPI, Pew), while advocacy and some policy groups produce higher numbers—FAIR estimates 18.6 million as of March 2025 [1] [2] [3]. Methodological differences (residual survey methods vs. alternative adjustments, inclusion/exclusion of parolees, and assumptions about arrivals and departures) drive most of the divergence in these counts [4] [3].
1. Why estimates differ: competing methods and definitions
The principal reason numbers diverge is methodological: Pew Research Center and the Migration Policy Institute (MPI) rely on residual methods applied to Census and survey data, producing mid‑2023 estimates near 13.7–14 million, while FAIR and some other groups adjust for presumed undercounts or count groups others treat as temporary, producing higher totals [1] [2] [3]. Pew explains its methodology in detail and notes revisions as new data arrive; it also flags that changes in parole and asylum policies alter who is counted as “unauthorized” [4] [2]. FAIR openly states estimating the size of the unauthorized population is an inexact science and urges skepticism about definitive figures [3].
2. What the recent trendlines show: rapid growth through 2023, then uncertainty
Multiple analyses agree the unauthorized population grew sharply through 2023—driven by large arrivals, parole programs and asylum flows—and reached record levels in that period [2] [1]. Pew’s 2025 report says the unauthorized population “reached a record 14 million in 2023” and that growth slowed after mid‑2024 when administrations tightened asylum and parole policies; for 2025 Pew says the population has “probably started to decline” though full 2024–25 estimates remain incomplete [2] [4]. FAIR’s later projection claims much larger growth to 18.6 million by March 2025, but that reflects different counting choices and assumptions [3].
3. Who is included or excluded matters a lot
Analysts differ about whether to count recent parolees, certain humanitarian arrivals, people who later obtained temporary protections, and those who have since been deported or left voluntarily. Pew notes many parole programs instituted under one administration were ended later, which changes whether those people are counted as “unauthorized”; it explicitly counts people whose protections are temporary because those statuses can rapidly change [2] [4]. FAIR’s framing uses a broader definition of “illegal alien” and explicitly disputes characterizations that treat some groups as lawfully present [3].
4. What the policy and political stakes are
Numbers affect debates over deportations, state sanctuary policies, budgets, and immigration enforcement. For example, the Congressional Budget Office and other institutions use different population scenarios in fiscal modelling; advocacy groups highlight higher totals to argue for stricter controls, while researchers emphasize uncertainty and data limits [3] [4]. Reporting from states and federal agencies through 2024–25 shows political decisions (pauses in parole, changes to asylum processing, and increased removals) have immediate effects on who is counted [2] [4].
5. Practical takeaway: a range, not a single fact
Current public estimates cluster in a broad range: mainstream research centers and MPI put the unauthorized population around 13.7–14 million for mid‑2023 and note growth through 2023 with possible declines after mid‑2024; alternative analyses like FAIR report higher totals (e.g., 18.6 million in March 2025) because they use different corrections and inclusion rules [1] [2] [3]. No single number is definitive; analysts emphasize that data gaps, rapid policy shifts, and undercounts mean reasonable, cited estimates will continue to differ [4] [3].
6. How to interpret future claims and what to watch for
When you see a headline figure, check (a) which organization produced it and their definition of “unauthorized” (b) what data and year it refers to, and (c) whether it adjusts for recent policy changes like parole rollbacks or deportation surges. Pew and MPI publish transparent residual‑method estimates and trend notes; groups like FAIR publish alternative adjustments and clearly state their assumptions—compare these explicitly before accepting a single number [4] [3] [1].
Limitations and note on sources: reporting remains incomplete for full 2024–25 coverage and different groups explicitly use divergent assumptions; this summary relies solely on the provided materials and does not assert facts beyond what those reports present [4] [3] [1].