The number of unauthorized immigrants peaked in 2007 at roughly 12 million


  1. After decades of rapid growth, illegal immigration into the U.S. has fallen since its 2007 peak.
  2. The declines remain tepid as the decrease in share from Mexico has been mostly offset by growth from Asia, Central America, and sub-Saharan Africa.
  3. Roughly 25 percent of current U.S. immigrants remain unauthorized.

According to Pew Research Center, the unauthorized immigrant population in the U.S.—now slightly above 11 million—has fallen and subsequently stabilized since 2007. Exact numbers differ, but even the US Department of Homeland Security noted declines in illegal immigration as far back as 2012.

And while Mexicans still constitute 52 percent of U.S. unauthorized immigrants, their share has been steadily declining. Plugging the gap, and therefore slowing the decline in overall illegal immigration, has been an influx of immigrants from Asia, Central America, and sub-Saharan Africa.


It seems as if popular perception of illegal immigration in the U.S. has yet to catch up with reality. According to Gallup, 59% of Americans were “worried a great deal or a fair amount” about illegal immigration in 2016—48% of Democrats and 78% of Republicans.

It’s not difficult to see why Americans’ views are resistant to change. According to Pew Research Center, “The recent relative stability in the estimated size of the U.S. unauthorized immigrant population is a contrast to previous periods.”


Interestingly, the U.S. government didn’t attempt to keep track of illegal immigration statistics until the 1970s. A 1982 GAO report explains why:

The illegal alien population is constantly in flux. Individuals enter and exit this population daily by making covert border crossings, by taking unauthorized employment, by failing to leave when their visas expire, by dying, and as a result of INS [Immigration and Naturalizations Service] decisions. Policymakers need to know the size of the population at particular moments and the volume of immigration over periods of time. Although illegal immigration has been a concern since the introduction of immigration curbs in 1875, deliberate attempts to estimate the population size reliably were not made until the 1970’s.

No matter what the data says, it’s clear that the accurate dissemination of the findings is equally as important.

Learn More

  1. Overall Number of U.S. Unauthorized Immigrants Holds Steady Since 2009 — Pew Research Center
  2. Why Is the Undocumented-Immigrant Population Dropping? — The Atlantic
  3. Immigration Data & Statistics — Department of Homeland Security