How many illegal aliens were accounted for intheU.S. during Biden administration? How many during Obama administration
Executive summary
The answer depends on which metric is used: border and enforcement “encounters,” releases/paroles, or researchers’ estimates of the resident unauthorized population — and those measures diverge sharply. Government and watchdog tallies show millions of border encounters and releases during the Biden years, while academic and policy groups offer competing population totals; by contrast, Obama-era enforcement recorded high annual removals and a documented multi-million deportation total across his presidency [1] [2] [3] [4] [5].
1. What “accounted for” can mean — encounters, releases, or resident population
“Accounted for” is applied variously by officials and analysts to mean encounters at the border, people paroled or released into the United States, or the total unauthorized resident population; DHS and congressional summaries track encounters and releases (for example reporting 10.8 million total encounters since FY2021 in one committee fact sheet) while demographers estimate the stock of unauthorized residents differently, producing divergent totals that all get quoted in public debate [1] [3] [2].
2. Biden administration — millions of encounters, millions released, population estimates vary
Published oversight and committee tallies describe huge enforcement activity since Biden took office: House Republicans reported figures such as 5.50 million single adults, 2.66 million family-unit individuals and 546,255 unaccompanied children encountered at the Southwest border since FY2021 and asserted totals of more than 10 million “encounters” since FY2021 [1]; independent fact-checkers and government lifecycle data have also been read to show roughly 2.5 million people released into the U.S. and roughly 2.8 million removed or expelled in initial processing during the early Biden period [2]. Demographic estimates of the unauthorized resident population after several years of Biden’s policies differ sharply: Pew’s mid‑2025 analysis placed the unauthorized population at a record 14 million in 2023, noting growth related to parole programs [3], while advocacy and research groups using different methods produced higher or lower totals — FAIR estimated 18.6 million in early 2025 [6] and Cato estimated a net population increase of roughly 5.5–6 million during Biden’s term [4]. All of these are working with different definitions and methods, which explains the wide range of numbers in public statements [3] [4] [6].
3. Obama administration — large removals over time, smaller resident-population growth
Under President Obama the enforcement record was characterized by large numbers of formal removals and, cumulatively, roughly three million noncitizens removed over his two terms according to several analyses [5] [7]. Yearly peaks included DHS reporting about 392,000 removals in FY2010 and other tallies showing removals near or above 400,000 in peak years such as FY2012 [8] [9]. At the same time, academic estimates indicate the undocumented resident population peaked then declined toward the end of the Obama years — research from the Center for Migration Studies and others documents slower population growth and even declines in some years, illustrating that high removals did not translate into large falls in the resident unauthorized population [10] [11].
4. Why direct “how many” comparisons are misleading without precise definitions
Comparing “how many illegal aliens were accounted for” under Biden versus Obama without locking down a single metric will produce conflicting answers: one can point to millions of encounters and releases under Biden [1] [2], but researchers’ resident‑population estimates range from roughly a pre‑Biden baseline of about 10–12 million in some DHS‑style counts to Pew’s later 14 million or higher claims from other groups [3] [4] [6]; conversely Obama’s administration removed roughly 3 million people over eight years while the undocumented population’s trajectory followed a different path [5] [8]. The sources themselves reflect policy and political agendas — congressional Republican fact sheets and advocacy groups emphasize encounter and release counts to argue a surge under Biden [1] [12], while demographic centers and independent analysts stress methodological differences and produce lower or more cautious resident‑population estimates [3] [4].
5. Bottom line: ranges and unavoidable caveats
Using sources collected here: enforcement tallies and committee reports document many millions of border encounters and several million releases/paroles during the Biden era [1] [2]; demographic estimates of the unauthorized resident population during or after Biden range from roughly the low‑teens (about 10–14 million, per DHS‑style and Pew analyses) up to higher independent estimates around 18 million depending on method [3] [4] [6]; under Obama, removals totaled about three million over his presidency with high single‑year removal counts in the 300,000–400,000 range [5] [8]. Because of differing definitions (encounters vs. released vs. resident population), any single‑number answer requires naming the metric being used [2] [5].