What are the annual net migration estimates for undocumented immigrants in the U.S. from 2021 to 2024?

1. How official agencies number the surge: CBO’s category-by-category read

The CBO breaks out a category it calls “other foreign nationals,” which it estimates had net immigration of about 830,000 people in 2021, roughly 2.0 million in 2022, 2.4 million in 2023 and 1.8 million in 2024 — a four‑year average of about 1.8 million and the clearest, published federal-derived series that isolates non‑traditional legal channels and many unauthorized flows ^[1].

2. The Census revision that changed the conversation: larger total NIM and methodology shifts

The Census Bureau’s Vintage 2024 revision substantially increased its Net International Migration figures — the agency reports jumping NIM by roughly 69.5% for July 2021–June 2022 and 101.7% for July 2022–June 2023 after adjusting for humanitarian migrants and administrative data, yielding total net immigration estimates of about 1.7 million (2021–22), 2.3 million (2022–23) and 2.8 million (2023–24) in the sequence used by demographers ^{[3] [2]}.

3. Who made up the increase: why analysts say it was mostly unauthorized migration

Multiple analyses — including Pew’s synthesis of Census revisions and demographic reweighting — conclude that legal immigration did not rise enough to account for the jump, implying the extra inflow through mid‑2024 was “almost entirely attributable to unauthorized immigration,” a conclusion drawn by pairing the Census NIM revision with ACS and administrative parole/release tallies ^{[2] [4]}.

4. Independent research and alternative tallies: MPI, CIS, Dallas Fed and NGOs

Migration Policy Institute and other independent trackers place the unauthorized population and inflows in the same surge narrative — MPI estimated roughly 13.7 million unauthorized residents by mid‑2023 (up from 12.8 million in 2022) while CIS and other groups report preliminary CPS and administrative-based counts pointing to multi‑million increases through early‑2024 — and the Dallas Fed documents inflows rising sharply from 2021, peaking in early 2024, then falling rapidly afterward ^{[5] [6] [7]}.

5. Range, uncertainty and why numbers differ: measurement, parolees, and “got‑aways”

Differences among CBO, Census-based adjustments and independent groups reflect definitional choices (total net migration vs. a category that isolates non‑documented and temporarily paroled populations), the inclusion or exclusion of large parole programs and administrative “releases,” and the undercount/coverage uncertainty in household surveys — the Census explicitly adjusted for humanitarian parolees and administrative data in Vintage 2024, while CBO and MPI use different administrative inputs and modeling choices, producing plausible annual net unauthorized‑migration figures that range roughly from under 1 million (early 2021) to about 2.4–2.8 million at the 2023–24 peak depending on the series used ^{[3] [1] [2] [5]}.

6. Reporting synthesis: best concise answer for 2021–2024

A balanced synthesis: annual net migration attributable largely to unauthorized immigrants is commonly estimated around 0.8–0.9 million in 2021, about 2.0 million in 2022, roughly 2.3–2.4 million in 2023, and about 1.8–2.8 million in the 2024 window depending on the series — CBO’s “other foreign nationals” gives 0.83M / 2.0M / 2.4M / 1.8M for 2021–24 ^[1], while the Census‑adjusted totals imply 1.7M, 2.3M and 2.8M for the overlapping 2021–22, 2022–23 and 2023–24 periods, with most analysts attributing the incremental growth primarily to unauthorized migration ^{[2] [3]}.

7. Caveats and what remains unresolved

These figures rest on evolving methodologies, provisional administrative counts (paroles, releases, “got‑aways”) and survey weights; researchers explicitly warn about undercount, definitional differences and the incompleteness of 2024 data in some series, so precise year‑to‑year undocumented inflows remain estimates rather than settled counts ^{[3] [6]}.