Which countries topped U.S. illegal immigration arrivals in 2020 versus 2025 by monthly border encounters?
Executive summary
In 2020 the largest share of monthly U.S. border encounters came from Mexico and the Northern Triangle (El Salvador, Guatemala, Honduras), with overall encounter totals depressed by the COVID-19 border restrictions in 2020 (monthly encounters fell sharply that year) [1]. By 2024–early 2025, encounters had shifted: Mexico remained a top country of citizenship for encounters in many months, but large year‑over‑year declines across Mexico and Northern Triangle nationalities produced near‑historic lows in monthly encounters by early 2025, with CBP and analysts reporting February–April 2025 monthly apprehensions in the single‑digit thousands for southwest border crossings between ports of entry (about 8,300 in February 2025 and 29,100 in January 2025 per CBP figures cited by reporters) [1] [2] [3].
1. What “topped” arrivals in 2020: Mexico and the Northern Triangle dominated
In 2020, monthly encounters were much lower than 2019 because pandemic-era restrictions reduced cross‑border movement, but the most common nationalities encountered historically and in that period were Mexico and the Northern Triangle countries (El Salvador, Guatemala, Honduras) — CBP data and Pew analyses show these nations were among the most common origin countries for migrants encountered at the U.S.–Mexico border around 2020 [1] [3]. Available sources do not list a month‑by‑month ranked table for every month of 2020 in the provided documents; they do, however, show the broad pattern that Mexico and the Northern Triangle were the leading sources [1].
2. What “topped” arrivals in 2025 by monthly encounters: big declines but Mexico still central
Reporting from early 2025 and CBP dashboards show that monthly encounters fell dramatically from 2024 into 2025, with January 2025 at roughly 29,100 encounters and February near 8,300 for between‑ports apprehensions — numbers far below the 2021–2024 peaks [2] [3]. Multiple sources note Mexico remained the highest single country of citizenship among CBP encounters during late 2024 and into 2025 even as encounters with Mexican citizens fell sharply [4] [5]. Thus, Mexico continued to “top” monthly counts in many months, though totals were much lower in early 2025 versus earlier years [4] [2].
3. How the metric “monthly border encounters” can mislead
“Encounters” combine different processes — Title 8 apprehensions, Office of Field Operations inadmissibles, and Title 42 expulsions — and since March 2020 CBP counts expulsions alongside apprehensions, changing comparability with pre‑2020 monthly figures [6] [7]. Analysts caution monthly encounter counts are an imperfect proxy for total migration or for net entries because they omit “gotaways” and mix expulsions with detentions; Migration Policy and Pew note shifts in policy and regional enforcement changed how many people show up in CBP tables [5] [8].
4. Policy and regional enforcement moved the needle, not just origin-country flows
The steep month‑to‑month declines seen by late 2024 and early 2025 reflect policy actions on both sides of the border — U.S. proclamations and rule changes plus much stronger enforcement by Mexican authorities — not solely changes in origin‑country push factors. Migration Policy reports Mexican authorities recorded more encounters than U.S. Border Patrol in many months between May 2024 and March 2025, which analysts say substantially reduced arrivals recorded by CBP [5]. DHS and the White House also point to proclamations and rules that produced large declines by late 2024–early 2025 [9] [10].
5. Competing narratives and political framing to note
Official DHS and White House statements frame the early‑2025 lows as proof of “the most secure border,” citing record‑low monthly totals [11] [8]. Congressional and advocacy fact sheets emphasize very large cumulative encounter totals since FY2021 and highlight “gotaways” and recidivism to argue policy failures under the prior administration [12] [13]. Independent analysts caution that the trend reflects a mix of policy, enforcement cooperation with Mexico, and counting changes — and that monthly encounter ranks by country therefore need context before being used as proof of long‑term shifts [5] [8].
6. What the available reporting does and does not show
Available sources document that Mexico and the Northern Triangle were dominant origin countries in 2020 and that Mexico remained a top country in 2024–25 even as monthly totals plunged in early 2025 [1] [2] [4]. The sources do not provide a single consolidated month‑by‑month ranked list comparing each specific month of 2020 with the corresponding month in 2025 for every nationality; therefore a definitive side‑by‑side monthly ranking by country for all months cannot be produced from the supplied material (not found in current reporting).
Bottom line: Mexico and the Northern Triangle were the leading source countries around 2020; by early 2025 Mexico still featured at or near the top for many months but absolute monthly encounter counts collapsed after policy shifts and intensified regional enforcement — a change driven as much by enforcement and counting rules as by origin‑country migration pressures [1] [5] [2].