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How many illegal immigrants have crossed the US-Mexico border since 2021?
Executive summary
Available reporting frames the question in terms of "encounters" — events when U.S. authorities apprehend, expel or deny entry to someone — rather than unique people. Most reputable tallies show roughly 6.5–11 million such encounters at the U.S.-Mexico or nationwide southern border since January 2021, with roughly 5.8–8.7 million of those occurring on the southwest land border, depending on the dataset and time window cited [1] [2] [3].
1. Encounters vs. unique people: the key statistical distinction
U.S. Customs and Border Protection (CBP) and analysts typically report "encounters," which count each time an individual is detained, expelled or processed — so repeat crossings by the same person produce multiple encounters. FactCheck notes DHS data showed 6.5 million encounters from February 2021 through October of a referenced year, including about 5.8 million apprehensions between ports of entry [1]. Pew and other analysts stress that recidivism was substantial in 2021 — over a quarter of encounters that year involved repeat crossers — so encounters overstate the number of distinct individuals [4].
2. Multiple published tallies — why the range (6–11 million)
Different outlets and institutions emphasize different measures and timeframes. FactCheck reported 6.5 million DHS encounters from Feb 2021–Oct [1]. The BBC and Congressional materials cited larger cumulative tallies: BBC reported "more than 10 million encounters" since January 2021, with about 8 million along the southwest land border [2]; the House Homeland Security Committee stated "more than 10.8 million encounters nationwide, including more than 8.72 million at the Southwest border" since FY2021 began [3]. Those higher figures extend through later dates or include broader encounter types (apprehensions, expulsions, inadmissibles) [5] [3].
3. Apprehensions, expulsions and "inadmissibles" — what counts in CBP data
CBP encounter data combines multiple categories: Border Patrol Title 8 apprehensions (people taken into custody), Office of Field Operations inadmissibles (people denied entry at ports), and expulsions under Title 42 or other authorities [5]. Wikipedia and CBP-based summaries note that fiscal year counts can include both apprehensions and expulsions; for example CBP reported more than 1.7 million detentions in FY2021 and 2.76 million in FY2022 — figures that feed into multi‑year encounter totals [6].
4. "Successful entries" and "gotaways" — an additional modeling challenge
Estimating how many people actually entered the U.S. without being detected requires modeling: USAFacts and DHS have attempted estimates of successful unauthorized entries by combining encounters, appraisal of apprehension rates, and other inputs. USAFacts cited a DHS estimate that around 660,000 people evaded apprehension on the southwest border in FY2021 [7]. Migration Policy Institute and others caution that these are modeled estimates with wide uncertainty because they must account for detection rates, repeat crossers, and removals [8] [9].
5. Political framing and competing narratives
Political actors use different figures to support conflicting claims. Some Republican committees and officials highlight the "10.8 million encounters" number to argue for a crisis [3]. Other outlets and analysts point to the encounters caveat and emphasize recidivism and expulsions to argue that headline counts do not directly translate into distinct new arrivals [1] [9]. The White House and DHS have also emphasized recent steep declines in encounters under new policies and bilateral enforcement, citing much lower monthly or FY2025 counts as evidence of progress [10] [11].
6. Recent trends matter — big rise then a fall
Reporting shows a sharp rise in encounters around 2021, with FY2021 reaching record annual encounter totals (about 1.66 million in Border Patrol encounters that fiscal year), followed by higher totals in 2022–2023 and then a marked decline after policy changes and increased Mexican enforcement in 2024–2025 [4] [8]. By later reporting in 2025, media outlets and DHS point to dramatically lower monthly and FY figures — for example, roughly 238,000 apprehensions recorded in FY2025 in one data snapshot — but those are for later periods and cannot be used to retroactively change cumulative encounter totals since 2021 [12] [11].
7. Bottom line and reporting limits
Available sources do not provide a single definitive count of "how many illegal immigrants have crossed" as unique people since 2021. Instead, public DHS/CBP data and mainstream analysis give a range of roughly 6.5 million to more than 10.8 million encounters since 2021 — with about 5.8–8.7 million of those on the southwest land border — but repeat crossings, expulsions, and modeling assumptions mean the number of distinct individuals who successfully entered is lower and harder to pin down [1] [2] [3] [7]. Reporters and policymakers must therefore be explicit about which measure they cite and the implicit agenda behind selecting a higher or lower figure.