Did President Biden let in the most illegal immigrants?

1. What the headline numbers actually measure

Journalistic and official summaries repeatedly warn that the metric most cited in public debates — CBP “encounters” — counts every stop, apprehension, detection or repeat attempt at the southern border, not a clean tally of distinct people who crossed and remained, so high encounter totals under Biden do not mechanically equate to a correspondingly sized permanent inflow ^{[3] [2]}.

2. The empirical record under Biden compared with Trump

Multiple outlets reported that encounters reached historic highs in the Biden years — for example, CBP recorded roughly 3.2 million encounters in 2023 compared with the 1.4 million peak under Trump in 2019 — a clear empirical contrast on that particular metric ^[1]. At the same time, other analyses emphasize that the government does not publish a definitive net count of unauthorized migrants who entered and stayed, so comparisons framed as “most illegal immigrants let in” over an administration are impeded by gaps in government data ^[3].

3. Why some political claims overstate the case

Hardline tallies circulated in opinion pieces and partisan claims — including wildly amplified figures like “20 million” under Biden — have been debunked or labeled misleading by fact-checkers because they conflate encounters with unique, permanent entries and often ignore expulsions, returns and repeat counts ^[2]. Even mainstream conservative commentary has produced inflated extrapolations ^[4], while independent fact-checking shows large increases in encounters but not a 1:1 translation to new long-term undocumented residents ^{[5] [2]}.

4. The larger picture: population estimates and trends

Nonpartisan demographic estimates indicate the total undocumented population rose to new highs during the Biden years — Pew and other research cited by Newsweek and others place undocumented population estimates above earlier figures — but those studies use sampling and modeling rather than a government ledger of individual entries, and they do not prove a causal policy “letting in” by the president ^{[1] [2]}. Analysts caution that increases reflect complex factors including global migration drivers, pandemic-era policies, enforcement choices and legal pathways, not a single executive decision ^{[3] [6]}.

5. Policy response and differing administrative approaches

The Biden administration responded to high encounter volumes with a mix of enforcement tightening, asylum rule changes and new legal pathways — Migration Policy notes Biden surpassed Trump in immigration-focused executive actions in his first three years and enacted policies intended to both deter irregular crossings and create alternatives to dangerous journeys ^[6]. By contrast, the Trump White House emphasized broad restrictions and proclamations on entry that it argued reduced crossings in some periods, though enforcement emphasis and metrics varied ^{[7] [8]}.

6. Political narratives and what they aim to accomplish

Republican messaging frames the situation as an active “letting in” under Biden to justify stricter controls, while Democrats and many policy analysts point to underlying causes and to distinctions between encounters, expulsions and net undocumented population estimates; each side highlights data that suits its policy aims, making neutral interpretation essential ^{[9] [4] [6]}.

7. Bottom line for the claim at hand

The claim that “President Biden let in the most illegal immigrants” is too blunt given the evidence: encounters did rise to historic levels in the Biden years and the undocumented population increased by many estimates, but key caveats — repeat counts, expulsions, lack of a definitive government count of net new residents, and differing definitions of “let in” — prevent a definitive verdict that Biden singularly “let in” the most illegal immigrants compared with other presidents ^{[1] [3] [2]}.