What metrics do demographers use to compare net immigration across presidential terms, and how did Biden-era net inflows compare to prior presidents?
Executive summary
Demographers and analysts compare presidential-era immigration using several quantifiable metrics—net international migration, change in the foreign‑born population, border “encounters,” and enforcement outcomes like removals/expulsions—each coming from different data systems and carrying distinct limits [1] [2] [3] [4]. Multiple authoritative series and recent revisions show the Biden years were associated with the largest net inflows in modern U.S. history, though the scale and composition of that increase depend heavily on which metric and dataset are used [1] [2] [5].
1. What demographers measure: net migration, foreign‑born stock, encounters, and enforcement
The central metric for demographers is net international migration—the difference between immigrants arriving and emigrants leaving—which directly feeds population projections and fiscal forecasts and is the basis of the Congressional Budget Office’s presidential-period comparisons [1]. Closely related is the measured change in the foreign‑born population from household surveys like the Census Bureau’s Current Population Survey, which reports stock increases (for example, a 4.5 million rise since January 2021 reported in CPS summaries) and yields monthly‑average growth rates used for short‑term comparisons [2]. Border authorities instead publish operational metrics—CBP “encounters” and monthly counts of migrants processed—useful for tracking irregular arrivals but not identical to net migration because they omit later outcomes and legal entries [3]. Enforcement metrics—deportations, expulsions, and repatriations—capture government action rather than net demographic change but are often invoked in political comparisons [6].
2. Why different metrics tell different stories: data sources and their blind spots
Net migration and foreign‑born stock yield population‑level effects but lag and depend on survey quality; the CPS and Census can undercount and need residual estimation methods, which critics note can overstate or misattribute illegal flows [7] [8]. Border encounter counts are timely but do not measure how many people ultimately stay, and the government does not publish a clean series of net illegal entries, complicating cross‑term comparisons [3]. Enforcement tallies—removals plus expulsions—can be large while actual in‑country populations also grow, because removals respond to flows and policy choices; for instance, combining expulsions and removals produced a large repatriation total under Biden even as the foreign‑born population rose [6].
3. The Biden years in headline numbers: big net inflows, many operational encounters
Multiple analyses concur that net inflows during the Biden administration were unusually large: Visual Capitalist, citing the CBO, shows the biggest net‑immigration increase under Biden for 2001–2024 (with 2021–2024 partly projected) [1], and the Census CPS recorded a roughly 4.5 million increase in the foreign‑born population since Biden took office, averaging about 137,000 net foreign‑born additions per month in early reporting [2]. Independent observers and policy shops put single‑year net migration in 2024 as high as 2.8 million in revised Census accounting, and some groups estimate multi‑year increases in the millions, much of it attributed to unauthorized or parole admissions [5] [7]. At the same time, operational enforcement totals were substantial: analyses note millions of encounters with many released and many removed, and combined repatriations/expulsions under Biden reached multi‑million counts in some tallies [4] [6].
4. Comparing Biden to predecessors: magnitude, composition, and context
By the population‑change measures used by demographers, Biden’s term stands out: net migration and foreign‑born stock increases in 2021–24 exceed recent presidents’ four‑year totals according to CBO/Census‑based reporting and secondary analyses [1] [5]. That does not mean every dataset or operational metric shows a simple “more migrants than under X” result—border encounter rates, enforcement emphases, parole programs, and policy signaling all changed across administrations—and some argue that measurement revisions and pandemic‑era disruptions complicate like‑for‑like comparisons [7] [3].
5. Reading the numbers: interpretation, political uses, and open questions
The empirical consensus in these sources is clear that net inflows rose sharply during the Biden administration in ways that produced record increases in the foreign‑born population by some measures, but the exact totals and the share that were unauthorized versus legal depend on the metric, survey adjustments, and revised Census estimates [1] [2] [5] [7]. Political actors selectively cite encounters, releases, or removals to support competing narratives—calls of a “surge” that overwhelmed the system versus rebuttals stressing enforcement actions and later declines—while demographers caution that no single operational count substitutes for population‑level net migration series [4] [9]. Several outstanding data challenges remain: reconciling encounter data with net population changes, accounting for survey undercounts and emigration, and incorporating recent policy shifts into multi‑year comparisons [3] [7].