This article presents estimates of the US undocumented population for 2017 derived by the Center for Migration Studies of New York (CMS). It focuses on the steep decline in the undocumented population from Mexico since 2010. While the president has focused the nation’s attention on the border wall, half a million US undocumented residents from Mexico left the undocumented population in 2016 alone, more than three times the number that arrived that year, leading to an overall decrease of nearly 400,000 undocumented residents from Mexico from 2016 to 2017. From 2010 to 2017, the undocumented population from Mexico fell by a remarkable 1.3 million.
For the past 10 years, the primary mode of entry for the undocumented population has been to overstay temporary visas. This article provides estimates of the number of noncitizens who overstayed temporary visas and those who entered without inspection (EWIs) in 2016 by the top five countries of origin.
Summary of Findings
- The US undocumented population from Mexico fell by almost 400,000 in 2017.
- In 2017, for the first time, the population from Mexico constituted less than one half of the total undocumented population.
- Since 2010, the undocumented population from Mexico has declined by 1.3 million.
- In California, the undocumented population from Mexico has declined by 26 percent since 2010, falling from 2.0 to 1.5 million; it also dropped by 50 percent in Alabama, and by one third in Georgia, New York, and New Mexico.
- The undocumented population from Venezuela grew rapidly after 2013, increasing from 60,000 to 145,000 in just four years.
- Visa overstays have significantly exceeded illegal border crossings during each of the last seven years.
- Mexico was the leading country for overstays in 2017, with about twice as many as India or China.
The estimates presented here were derived by CMS based on information collected in the Census Bureau’s annual American Community Survey (ACS). The procedures used to derive detailed estimates of the undocumented population are described in Warren (2014). CMS used its annual estimates of the undocumented population for 2010 to 2017 — by state of residence, country of origin, and year of entry — to compile the information described here. Additional methodological details appear as footnotes or as notes in the tables.
 In 2016, the US undocumented population from Mexico that arrived before 2016 was 5.6 million; one year later, in 2017, the number that arrived before 2016 had dropped to 5.1 million, indicating that half a million had left the undocumented population from Mexico.
 Undocumented residents leave the population by being removed, emigrating voluntarily, adjusting to permanent legal status, or dying.