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How has the number of undocumented immigrants in the US changed since 2020?
Executive summary
Estimates of the number of undocumented (unauthorized) immigrants in the U.S. rose sharply after 2020, with Pew Research Center reporting a jump from roughly 10.5 million in 2021 to a record 14 million in 2023 — an increase of about 3.5 million — and many analysts saying growth continued into early 2024 before slowing and possibly reversing in 2025 [1] [2]. Alternative estimates and partisan-leaning groups put very different totals for 2025 — for example FAIR reports 18.6 million in March 2025 — illustrating wide methodological disagreement and large uncertainty in recent years [3] [4].
1. Sharp growth after 2020, led by recent arrivals
Multiple research groups document a notable uptick in the unauthorized population after 2020. Pew’s revised accounting shows the unauthorized population reached a record 14 million in 2023, driven by a wave of recent arrivals that added roughly 3.5 million between 2021 and 2023 [1]. Migration Policy Institute and others describe record U.S.–Mexico border encounters and an “expansion amid record U.S.-Mexico border arrivals” that contributed to those higher totals [5] [6].
2. Why estimates diverge: methods and undercounts
Estimates vary widely because methods — surveys, administrative counts, imputations, and adjustments for undercounting — give different pictures. Pew, MPI, CMS and academic teams adjust Census and ACS data to account for undercounts of recent arrivals; advocacy or enforcement-oriented groups use alternative models and assumptions that can produce much higher or lower figures. FAIR’s March 2025 estimate of 18.6 million exemplifies the upper end of the range and rests on different assumptions about undercount and arrivals since 2020 [3] [4].
3. Timeline: growth through 2023–early 2024, then slowdown
Available analyses indicate continued population growth through early 2024, then a slowing in the latter half of 2024 after policy shifts (pauses in parole and asylum intake) and subsequent enforcement changes; Pew notes growth slowed in mid‑to‑late 2024 and that monthly CPS data point to a decrease in the total immigrant population by June 2025 [2] [7]. Several commentators trace the mid‑2024 inflection to policy changes that reduced new admissions and parole programs [2].
4. Signs of a 2025 decline — but with caveats
Some data and administrative signals point to a possible decline in 2025: Pew says the unauthorized population “has probably started to decline” in 2025 and that CPS monthly data show the total immigrant population decreased by June 2025, implying a fall in the unauthorized share as well [2] [7]. However, Pew and others caution that 2024–2025 data are incomplete, trends depend heavily on rapid policy shifts (including large-scale revocations of parole and increased deportations under the 2025 administration), and definitive estimates for 2024–2025 are not yet possible [2] [7].
5. Alternative narratives and political uses of numbers
Different actors use these numbers to support opposing narratives. Enforcement-focused groups and some officials cite large estimates or short‑term declines to argue for restrictive policies or to claim success in removals [3] [8]. Advocacy or academic organizations emphasize methodological rigor and uncertainty, warning against overinterpreting preliminary CPS or encounter data and highlighting the challenges of measuring a mobile, often hidden population [7] [5]. News outlets note officials’ claims of sizable departures (for example, a 1.6 million decline asserted by DHS officials) but also report researchers saying “it’s too soon to know” and that survey response issues complicate interpretation [8].
6. Broader immigrant population context
The unauthorized population is one part of a larger surge in the foreign‑born population: the overall immigrant stock rose to historical highs (53.3 million by January 2025) even as the mix of lawful and unauthorized residents shifted, and some reports show the U.S. experienced an unprecedented number of arrivals between 2020 and 2025 [9] [10]. That context matters because changes in the total foreign‑born population affect survey denominators and undercount adjustments used to estimate unauthorized totals [10] [1].
7. Bottom line — clear trend but uncertain magnitude
The best available mainstream research shows a clear pattern: relative stability pre‑2020, a marked rise in unauthorized residents after 2020 (about +3.5 million from 2021–2023 per Pew), possible continued growth into early 2024 followed by slowing, and preliminary signs of decline in 2025 tied to policy and enforcement shifts [1] [2] [7]. Yet alternative estimates (e.g., FAIR’s 18.6 million) and methodological disputes mean the exact count and the size of any 2025 decline remain contested and uncertain [3] [4].
Limitations: reporting on 2024–2025 relies on incomplete CPS and administrative data; Pew and other researchers explicitly warn definitive 2024–2025 estimates aren’t yet possible and trends could reverse with policy changes [2] [7].