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What are the differences between 'encounters,' 'apprehensions,' and estimates of total illegal border crossings?
Executive summary
Encounters are CBP’s broad count of any contact with a noncitizen (including Title 8 apprehensions, OFO inadmissibles, and Title 42 expulsions); apprehensions are a narrower category meaning physical control or temporary detainment by U.S. Border Patrol between ports of entry; and independent estimates of total illegal crossings (including people who evade detection or later overstay visas) are not directly reported by CBP and require outside modelling or foreign partner data (CBP definitions: [1], [2], [3]; Mexico recorded more encounters than USBP in 2024–25: [4]).
1. What “encounters” captures — CBP’s wide net
CBP’s published “encounters” totals combine three operational streams: USBP Title 8 apprehensions (between ports of entry), OFO Title 8 inadmissibles (people denied at ports of entry), and Title 42 expulsions; the agency treats the encounters figure as a comprehensive count of contacts recorded across land, air and sea but warns the data can change as records are corrected or reclassified [1] [5].
2. What “apprehensions” specifically means — physical control between POEs
“Apprehensions” in CBP/USBP usage refers to the agency taking physical control or temporarily detaining a person who is not lawfully in the U.S. and who was encountered between ports of entry; an apprehension may or may not lead to a formal arrest or criminal charge, and it historically has been the specific metric for unauthorized crossings intercepted on the border [2] [3].
3. “Inadmissibles” and “Title 42 expulsions” — separate pieces of the puzzle
Inadmissibles are people encountered at ports of entry who seek lawful admission but are determined inadmissible or withdraw applications; Title 42 expulsions are a public‑health removal category that CBP records separately — both categories are included in overall encounter totals, which is why “encounters” exceed pure USBP apprehensions [1] [2].
4. Why encounters ≠ total attempted or successful illegal crossings
CBP’s encounter counts measure recorded contacts, not all attempts or successful undetected entries. The agency and academic analysts note that encounters omit people who evaded detection entirely and those who later overstayed legal admissions; therefore independent estimates of “total illegal crossings” require modeling or additional data sources beyond CBP encounters (available sources do not mention a CBP estimate of total undetected or later‑overstay illegal presence) [3] [6].
5. Outside or complementary measures — Mexico and research groups
Migration researchers point to complementary datasets: for example, Mexican authorities recorded more encounters than U.S. Border Patrol every month between May 2024 and March 2025 — a reminder that bilateral data can change the picture of cross‑border movement and that CBP’s USBP encounters are a U.S. operational view, not a full accounting of regional flows [4]. The Migration Policy Institute uses CBP encounters but also highlights the need to combine datasets to understand real flows [4].
6. How CBP changed reporting and why comparisons over time require care
CBP changed how it aggregates metrics: beginning in March FY2020, USBP and OFO encounter statistics started to include both Title 8 apprehensions/inadmissibles and Title 42 expulsions in the “encounters” total. That methodological shift means long‑term comparisons require attention to definitions and to when expulsions were folded in [3] [2] [7].
7. Political framing and competing narratives
Federal statements and congressional offices interpret the same CBP counts differently: the Department of Homeland Security touts record‑low nationwide encounters and low apprehension numbers as a sign of enforcement success (e.g., low monthly nationwide encounter and apprehension figures cited by DHS) while Republican House committees emphasize dramatic year‑over‑year drops in Southwest border encounters and USBP apprehensions to argue for policy changes — both sides use the same CBP categories but highlight different timeframes and subsets [8] [9] [10].
8. Practical takeaway for readers
When you see headlines citing “encounters,” check whether the story means total CBP encounters (a blended count), USBP apprehensions (detentions between ports of entry), or a modeled estimate of all crossings (which CBP does not publish). Also check whether Title 42 expulsions or OFO inadmissibles are included and whether temporal comparison spans a pre/post‑March 2020 reporting change [1] [2] [3].
Limitations and final note: CBP’s published definitions and datasets explain what is counted, but available sources do not provide a CBP estimate of total undetected or later‑overstay crossings — that figure requires modeling or third‑party datasets (available sources do not mention a CBP total for undetected entries) [3] [6].