How many migrants crossed the US border illegally vs how many overstayed visas in 2024?
Executive summary
In recent years official and academic sources show visa overstays have contributed more to the growth of the undocumented population than illegal crossings at the southern border; DHS and research groups report hundreds of thousands of overstays annually (for example, DHS estimated roughly 416,500 overstays in one recent year) while Border Patrol “encounters” peaked near 249,740 in December 2023 but represent detected attempts rather than unique people [1] [2]. Exact 2024 totals for unique individuals who crossed illegally versus those who overstayed are not published in a single definitive tally in the available reporting [3].
1. Why the question matters: two different processes, two different metrics
“Crossed the border illegally” is typically measured by CBP as “encounters” (apprehensions, expulsions and inadmissibles), which count interactions and can include repeat attempts by the same person; “visa overstays” are measured via DHS entry/exit comparisons and report how many nonimmigrant arrivals remained past authorized departure dates. These are fundamentally different data streams and not directly additive without careful reconciliation [4] [5] [1].
2. What the data say about visa overstays
DHS entry/exit data and analysts have shown annual visa overstays in the hundreds of thousands. One DHS-derived summary cited an estimate of roughly 416,500 overstays among about 45 million air/sea arrivals in a recent year; other reporting and advocacy groups note that overstays have outnumbered new undocumented arrivals via illegal border crossings for many years [1] [6] [7].
3. What the data say about illegal border crossings in 2024
CBP encounter totals rose through 2023 and peaked in December 2023 at about 249,740 detected crossing attempts; reporting indicates crossings decreased through 2024 but encounter numbers still reflect attempts, not unique people, and include expulsions under Title 42 and other policies that changed enforcement counts [2] [3]. USAFacts’ sector reporting and CBP make clear that September–December comparisons and policy shifts can move encounter counts dramatically [2].
4. Why simple comparisons are misleading
Multiple sources warn against equating encounter counts with unique migrants: encounters can double- or triple-count repeat crossers and do not capture undetected “gotaways.” Overstay tallies typically cover air and sea arrivals only and exclude land-entry visitors, complicating apples-to-apples comparisons. Analysts and DHS say both measures have limits and require careful interpretation [1] [3] [4].
5. Consensus across independent sources
Research organizations (Center for Migration Studies, American Immigration Council), government reports, and neutral analysts repeatedly find that visa overstays now account for a larger share of the growth of the undocumented population than unauthorized border crossings—this pattern is described as the “new normal” by researchers and appears in multiple reports going back several years [8] [6] [7].
6. Numbers you can cite with confidence—and their caveats
You can cite DHS entry/exit estimates (e.g., ~416,500 overstays in a reported year) and CBP encounter peaks (e.g., 249,740 encounters in Dec. 2023), but both carry caveats: overstays reflect air/sea cohorts and known records; encounters count interactions and can include repeat attempts and expulsions under shifting policies [1] [2] [4].
7. Competing viewpoints and hidden incentives
Advocates for border barriers emphasize encounter counts and dramatic sector spikes to argue for physical controls; proponents of entry/exit systems highlight overstays to argue for better tracking of air/sea travel. Some advocacy groups (e.g., FAIR) frame overstays as a “crisis” to push punitive legislation, while immigration researchers urge policy balanced toward entry/exit systems and targeted enforcement [9] [6] [7].
8. What reporting does not provide (limitations)
Available sources do not publish a definitive 2024 figure that reconciles unique individuals who crossed illegally versus unique visa overstays for the same calendar year. There is no single public dataset that converts CBP encounters into a distinct-person count or that fully covers land-entry overstays in the DHS summaries cited [3] [5] [1].
9. Practical takeaway for readers
If your aim is to understand where new undocumented residents originate, rely on DHS overstay reports and peer-reviewed CMS analyses that show overstays are a leading source; if you want to understand enforcement pressure and operational workload, use CBP encounter data—but always note their methodological differences and policy-driven fluctuations [5] [1] [2].
Limitations: this summary uses the provided reporting and government summaries; many sources concur that overstays now outnumber detected illegal crossings, but a reconciled, single-year count of unique individuals for 2024 is not available in the materials reviewed [8] [3] [1].