What you need to know
Although public debate often treats unauthorized immigration as strictly a border issue, millions of people without legal status live and work far from U.S. points of entry. In this brief, we examine who is living in the U.S. without authorization and where they live.
- We report on the number of undocumented individuals and the percentage of foreign-born living in the U.S.
- We identify the 10 states with the highest percentages of the undocumented population, as well as counties in the remaining 40 states with large undocumented populations.
How many people live in the U.S. without authorization?
Before the COVID-19 pandemic, estimates of unauthorized immigrants in the U.S. hovered around 11 million. By 2023, the number grew to 13.7 million. Today, estimates range from 11 to 18 million, reflecting uncertainty due to policy changes, border activity, and limited data.
The chart below shows an alternate measure that uses Census data to show the percentage of the U.S. population (including citizens, authorized immigrants, and undocumented individuals) that is foreign-born.
In 1970, foreign-born individuals made up just 4.7% of the U.S. population. By 2025, that number has risen to 15.8%, the highest share since 1910.
The figure below shows the ten states with the highest shares of unauthorized immigrants. California is home to about a quarter of the nation’s total, with roughly 2.7 million people. Texas, Florida, New York, and New Jersey round out the top five.
While major cities in the top-10 states like Los Angeles and New York have large unauthorized populations, some urban and suburban areas in the remaining 40 states also have substantial undocumented populations. The figure below shows the counties (along with the associated city) with the highest undocumented populations in the 40 states omitted from the chart above.
Why are people unauthorized?
A large number of undocumented immigrants are not people who crossed the border illegally. An estimated 43% entered the U.S. legally and overstayed a visa. Others are awaiting asylum decisions or other legal determinations. The generally slow immigration adjudication process in the U.S. means many individuals remain unauthorized in the face of pending asylum claims.
The Takeaway
The unauthorized population in the U.S. has increased since the COVID pandemic.
Unauthorized immigrants are not confined to border regions or blue states.
The undocumented live across the U.S., including in some rural and suburban communities, and arrive through a variety of legal and illegal pathways.
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Further reading
Office of Homeland Security Statistics. (2025). Estimates of the Illegal Alien Population Residing in the United States https://tinyurl.com/2pna99aj (Accessed 8/8/2025)
Center for Immigration Studies. (2025). Foreign-born number and share of U.S. population at all-time highs in January 2025. https://tinyurl.com/4zcj4b6f (Accessed 7/23/2025)
Sources
U.S. Census Bureau. (2024). The foreign-born population: 2022 American Community Survey brief. https://tinyurl.com/y4zv9eke (Accessed 7/23/2025)
The White House. (2025). Declaring a national emergency at the southern border of the United States [Presidential proclamation]. https://tinyurl.com/2uyf23yx (Accessed 8/8/2025)
American Immigration Council. (2020). Immigrants in Utah. https://tinyurl.com/53w5zfnp (Accessed 8/8/2025)
Migration Policy Institute. (N.D.). Profile of the Unauthorized Population: Gwinnett County, Georgia. https://tinyurl.com/5n7dh9ru (Accessed 8/8/2025)
American Immigration Council. (2020). Immigrants in Arizona. https://tinyurl.com/ar23cc2n (Accessed 8/8/2025)
Migration Policy Institute. (2024). Unauthorized immigrant population profiles. https://tinyurl.com/3fwrv98p (Accessed 8/8/2025)
Migration Policy Institute. (2024a). A turning point? New data show unauthorized immigrant population in U.S. rebounding. https://tinyurl.com/3wbp4rfp (Accessed 7/23/2025)
Contributors
Lindsey Cormack (Content Lead) is an Associate Professor of Political Science at Stevens Institute of Technology and the Director of the Diplomacy Lab. She received her PhD from New York University. Her research explores congressional communication, civic education, and electoral systems. Lindsey is the creator of DCInbox, a comprehensive digital archive of Congress-to-constituent e-newsletters, and the author of How to Raise a Citizen (And Why It’s Up to You to Do It) and Congress and U.S. Veterans: From the GI Bill to the VA Crisis. Her work has been featured in The New York Times, The Washington Post, Bloomberg Businessweek, Big Think, and more. With a drive for connecting academic insights to real-world challenges, she collaborates with schools, communities, and parent groups to enhance civic participation and understanding.
William Bianco (Research Director) is Professor of Political Science at Indiana University and Founding Director of the Indiana Political Analytics Workshop. He received his PhD from the University of Rochester. His teaching focuses on first-year students and the Introduction to American Government class, emphasizing quantitative literacy. He is the co-author of American Politics Today, an introductory textbook published by W. W. Norton, now in its 8th edition. He has authored a second textbook, American Politics: Strategy and Choice. His research program focuses on American politics, encompassing Trust: Representatives and Constituents and numerous articles. He was also the PI or Co-PI for seven National Science Foundation grants and a current grant from the Russell Sage Foundation on the sources of inequalities in federal COVID assistance programs. His op-eds have been published in The Washington Post, Indianapolis Star, Newsday, and other venues.
An earlier version of this brief was researched in July 2023 by Policy vs Politic interns Mary Stafford and Zul Norin, drafted by Griffin Reid, and edited by Dr. Nicholas Clark and Dr. William Bianco, with the assistance of subject matter expert Dr. Alexandra Filindra.
