Which metropolitan areas and border counties within high-immigration states have the highest concentrations of undocumented residents in 2025?
Executive summary
In 2025 unauthorized immigrants remain concentrated in a small set of large metropolitan areas—above all the New York and Los Angeles metros—and are still disproportionately located in a handful of high‑immigration states including California, Texas, Florida, New York, New Jersey and Illinois [1] [2]. Migration Policy Institute and Pew Research underline that county‑level concentrations persist (MPI’s top county profiles and a 135‑county list), but public datasets show dispersion from the traditional six‑state core and significant uncertainty about exact 2024–25 shifts [3] [4] [5].
1. The metro map: New York and Los Angeles still top the list
The largest concentrations of unauthorized immigrants are in the nation’s biggest immigrant hubs, led by the New York and Los Angeles metropolitan areas, which MPI and other analysts identify as the two largest metro destinations for immigrants generally and for unauthorized residents in particular [1] [5]. Migration scholars and the Migration Dialogue mapping show most immigrants live in about a dozen metros, with New York and Los Angeles represented by the largest circles on national maps of immigrant settlement [1]. Pew and MPI reporting reinforce that large, established metros continue to host the highest totals even as growth since 2021 shifted numbers upward in multiple gateways [6] [7].
2. Border counties: many are among the highest‑concentration counties, but specific names depend on the data tool
Analysts at MPI and others note that the 135 counties with the largest unauthorized populations include numerous U.S.–Mexico border counties and longstanding interior county hubs, reflecting both historical settlement and recent arrivals [3] [4]. Migration Policy’s county profiles are the most granular public source for identifying which border counties currently rank highest, but the snippets provided do not list county names directly; therefore this account can confirm that border counties are prominent in MPI’s top county roster without asserting a definitive ranked list of counties from the supplied excerpts [3] [4]. Other reporting and data visualizations place high concentrations in border regions of California, Texas, Arizona and New Mexico, but precise 2025 county rankings require consulting MPI’s county data tool or other county‑level tables [4] [8].
3. Why those metros and border counties concentrate unauthorized populations
The drivers are structural: long‑standing immigrant networks, labor demand in sectors like services and maintenance, and recent large flows processed at the border and paroled or released into the country, which swell populations in established gateway metros and neighboring counties [1] [6]. MPI and Pew tie recent expansion in the unauthorized population to record border encounters and large numbers of Border Patrol releases and parolees between 2021 and mid‑2024—administrative flows that feed both border counties and interior metros where migrants join kinship and labor networks [6] [7]. At the same time, analysts note a modest deconcentration trend compared with earlier decades—the top six states held a far larger share in 1990 than they did by 2022—so newer settlement outside the traditional gateways also matters [5].
4. Conflicting estimates and data limits: how to read 2025 rankings
Estimates vary widely: Pew’s 2025 reporting and MPI place the unauthorized population at record highs and highlight metro and county concentrations, but advocacy and research groups offer different totals and geographic emphases—e.g., FAIR’s far larger national estimate—illustrating political and methodological divergence in the field [6] [9]. Government administrative series (CBP, DHS, CBO) provide near‑real‑time encounter counts that explain recent inflows but do not substitute for population estimates, and MPI cautions that county‑level ranking depends on its imputation methodology and the latest ACS/SIPP weighting [10] [4] [8]. For a definitive ranked list of the highest‑concentration border counties in 2025, the MPI county profiles and Pew’s state/metro tables are the appropriate primary sources to consult directly [3] [6].