In 2010 how many undocumented or illegals were in the USA
Executive summary
Contemporary, widely cited estimates place the unauthorized (undocumented or “illegal”) immigrant population in the United States in 2010 at roughly 11 million to 11.5 million people, with Pew’s March‑2010 estimate at 11.2 million and DHS‑related series near 11.4–11.6 million [1] [2]. Scholars and advocacy groups note important uncertainty: alternative methodological choices produce lower and notably higher estimates—ranging in some studies from about 10.8 million up to a controversial model‑based estimate of 22.1 million—so any single number must be read as a method‑dependent estimate, not a census count [3] [4].
1. The conventional consensus: roughly 11 million in 2010
Major demographic centers converged on a value near 11 million for 2010: the Pew Hispanic Center’s March 2010 estimate was 11.2 million unauthorized immigrants, a figure described as “virtually unchanged” from 2009 and below a mid‑decade peak [1], while DHS and other official series put estimates in the same neighborhood — often reported as roughly 11.4–11.6 million for the 2010/2011 period [2] [5]. Those mainstream series use the residual estimation method: starting with survey counts of the foreign‑born, subtracting legally resident foreign‑born, and treating the residual as the unauthorized population after adjustments for undercount [6] [7].
2. Why even the “11 million” number is an estimate, not a headcount
All leading estimates rely on indirect methods because there is no administrative census of unauthorized status; the common “residual” approach uses American Community Survey or census microdata and makes adjustments for undercount and legal status classifications [8] [6]. DHS, Pew, CMS and academic teams differ in how they adjust for undercount, which country‑specific ratios they apply, and how they treat temporary entries and emigration, producing modest but material differences — Pew and CMS estimates have historically been 5–10% lower than some DHS series [5] [8].
3. Alternative estimates and why they diverge
Scholars have produced very different totals by changing key assumptions: some academic demographic‑modeling work has argued for a substantially larger population — a 2018 PLOS ONE study produced a mean estimate of 22.1 million for the 1990–2016 period, asserting that operational data on deportations and overstays combined with demographic modeling imply a much larger “hidden” stock [4] [9]. Conversely, other analyses produce lower decade‑level flows or emphasize out‑migration to argue for smaller counts; the spread from roughly 10.8 million (Hoefer, Rytina and Baker) to 22.1 million reflects sensitivity to assumptions about entry, voluntary return, mortality, and undercount [3] [4].
4. What changed around 2007–2010: geography and composition
The population estimate stabilized and slightly declined after a 2007 peak; Pew and related analyses attribute the post‑2007 decline and flattening to fewer entrants from Mexico and to economic and enforcement changes, with the Mexican undocumented population falling from about 7 million in 2007 to roughly 6.5 million in 2010 [1]. Reporting also notes that births to unauthorized immigrant parents and the long‑standing concentration of the unauthorized population in a handful of states shape annual totals and measurement sensitivity [1] [10].
5. Reading the disagreement: methodological choices and stakes
Differences in headline numbers are not merely academic; they stem from explicit methodological choices — which survey to base counts on (ACS vs. CPS), how to correct for undercount, treatment of visa‑overstays and departures, and the demographic parameters fed into models [8] [6] [4]. These choices carry policy and political stakes because larger or smaller estimates are used by different actors to argue for stricter enforcement, broader legalization, or shifts in resource allocation; some think‑tank critiques and competing reports (e.g., CIS analyses or Yale‑team modeling) reflect distinct institutional perspectives and incentives that readers should weigh alongside technical transparency [11] [9].
Conclusion: best short answer
Based on the mainstream, method‑transparent residual estimates used by Pew, DHS and CMS, the best straightforward answer is that about 11–11.5 million unauthorized immigrants resided in the United States in 2010 [1] [2] [5]; however, researchers using different modeling assumptions have produced substantially different totals, so that figure should be treated as an informed estimate rather than a definitive headcount [4] [6].