By Robert Warren

In 2021, the undocumented population residing in the United States (US) increased slightly to 10.3 million, compared to 10.2 million the previous year. The gradual decline or near-zero growth of this population has continued for more than a decade. However, the large increases in apprehensions at the southern border in recent years, along with continued legislative gridlock in Congress, could portend a new era of growth of this population. Unfortunately, the data needed to determine whether the population will enter a period of growth after 2021 — or whether the era of near-zero growth will continue — will not be available for at least a year or two. The most accurate demographic estimates of the undocumented population are derived from data collected in the US Census Bureau’s American Community Survey. Estimates of the size of the undocumented population in 2022 will not be available until early 2024.

This report focuses on the most significant trend in the undocumented population in the past decade — the remarkable decline of 1.9 million in the undocumented population from Mexico from 2011 to 2021. The decline for Mexico in this period was 600,000 more than the total population increase from the seven countries (in order) with the fastest growing US undocumented populations: Guatemala, Honduras, India, Venezuela, El Salvador, Brazil, and China. This paper finds that:

• The long-term decline, or near-zero growth, of the total undocumented population that began in 2008 continued in 2021.

• The percent of undocumented residents in the total US population declined from 3.8 percent in 2011 to 3.1 percent in 2021.

• The undocumented population from Mexico declined from 6.4 million in 2011 to 4.4 million in 2021, a drop of 1.9 million in 10 years.

• A total of 2.9 million, or 47 percent, of the US undocumented population from Mexico in 2011 had left the undocumented population by 2021.

• The drop in the undocumented population from Mexico from 2011 to 2021 occurred nationwide, and the decline affected the undocumented population in nearly every state.

• The fastest growing undocumented populations by country in the last 10 years were from Guatemala, Honduras, India, El Salvador, Venezuela, and Brazil. The combined undocumented populations from these six countries grew by 1.2 million.

• Countries that had declining populations after 2011 included Poland, Peru, Ecuador, Korea, and Philippines, in addition to the large drop for Mexico.

• California had the largest decline in undocumented residents — 665,000 from 2011 to 2021. The undocumented population from Mexico living in California during this period declined by 720,000.

• The combined undocumented population in California, New York, and Illinois fell by more than one million from 2021 to 2011.

Journal on Migration and Human Security Volume 0: Ahead of Print, 2023.