Which regions experienced the largest declines in undocumented population in 2025?
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Executive summary
Regional data in available reporting points to the Southwest — especially the U.S.-Mexico border sectors such as San Diego and broader states like California — as where the largest declines in the undocumented or overall foreign‑born population occurred in 2025, with national-level drops ranging from roughly 1 million to more than 2 million depending on the analyst (Pew: unauthorized population likely fell by as much as 1 million Jan–Jun 2025; CIS and others report foreign‑born declines of ~957,000 Jan–May and ~2.23 million Jan–Jul 2025) [1] [2] [3] [4]. Policymakers and researchers disagree on magnitude and geographic concentration because of differing methods and possible undercounts in survey and administrative sources [5] [6].
1. Southwest and border sectors show the sharpest contractions
Multiple sources point to the southwestern border region as the flashpoint for declines: analysts reporting declines in detected crossing attempts identify the San Diego sector as experiencing the largest drop in detected crossings (96.5% year‑over‑year in one account), and news and research outlets describe policy changes and heightened enforcement concentrated at the southern border and in states such as California that yielded large local population losses [4] [7] [5]. These border‑sector declines are consistent with both fewer arrivals and increased departures or removals anchored in the region [4] [5].
2. National totals differ widely; that shapes regional attributions
Estimates vary: Pew’s analysis says the unauthorized population “likely declined, possibly by as much as 1 million” between January and June 2025, while analysts using raw CPS microdata put foreign‑born declines near 957,000 from January–May and as much as 2.23 million from January–July 2025 (Center for Immigration Studies) [1] [2] [3]. The larger CPS‑based declines imply broader geographic dispersion — not only border states but also jurisdictions with high immigrant concentrations — while the more conservative Pew framing emphasizes likely decline concentrated among the unauthorized and influenced heavily by border and enforcement changes [1] [6].
3. Methodology disputes undercut precise regional rankings
Pew warns that survey participation and Census/CPS methodology changes affect estimates, and that heightened enforcement may have suppressed response rates among undocumented people, potentially biasing geographic patterns [6] [5]. The San Francisco Fed and Congressional Budget Office cite administrative reductions in releases and net migration that disproportionately affect border sectors, but each uses different input data (CBP releases, CPS, administrative flows), meaning regional magnitudes depend on which dataset an analyst prioritizes [8] [9].
4. Enforcement and policy explain concentrated declines — and competing narratives
Reporting and commentaries link the declines to 2025 policy shifts: increased removals, executive actions on asylum and parole, and tighter border releases reduced entries and increased departures, especially from Latin American origin groups concentrated in southwestern states [5] [6] [9]. Proponents of stricter enforcement cite labor‑market and demographic benefits from a reduced undocumented population; critics warn that fear and undercounting could exaggerate drops and that departures disrupt communities and essential workforces [3] [5].
5. Which regions lost the most people — assessment and limits
Available sources most consistently point to the U.S. Southwest (San Diego sector, California broadly, and the southern border corridor) as experiencing the largest proportional and absolute decreases tied to fewer crossings and tightened releases [4] [7]. National‑level CPS analyses suggest large drops in foreign‑born populations that would also implicate populous states with big immigrant communities [2] [3]. However, precise state‑by‑state rankings are not provided in the cited pieces; Pew and other analysts caution that survey undercount and methodological shifts limit our ability to map exact regional losses [1] [6].
6. What’s missing and how to interpret competing claims
None of the provided sources offers a definitive, standardized state‑level breakdown of undocumented declines for all of 2025; Pew reports likely nationwide declines and points to mid‑year patterns, the CIS and other analysts present larger CPS‑based drops, and researchers such as the San Francisco Fed and CBO emphasize administrative flow changes [1] [2] [8] [9]. Given these differences, the most defensible conclusion is directional: largest declines concentrated in the Southwest and border sectors, with secondary losses in high‑immigrant states — but exact magnitudes and rankings depend on the dataset and method used [4] [3] [6].
7. Bottom line for readers
Experts agree 2025 saw substantial declines in the undocumented/foreign‑born population and that the Southwest and border sectors account for a major share of that drop; they disagree sharply over how large the decline was and how broadly it extended inland. Use Pew’s cautious, methodologically aware framing for conservative estimates (possible –1 million unauthorized Jan–Jun) and CPS‑raw estimates for larger, more geographically dispersed effects (–957,000 to –2.23 million foreign‑born Jan–May/Jan–Jul), but recognize both approaches note limits from undercounts and policy‑driven response changes [1] [2] [3] [6].