Following Years of High Border Arrivals, the U.S. Unauthorized Immigrant Population Hits New Peak

The Migration Policy Institute (MPI) estimates that approximately 15.8 million unauthorized immigrants lived in the United States as of mid-2024, after hovering in the 11 million range throughout the decade beginning in 2010. The increase is primarily driven by record unauthorized migrant arrivals at the U.S.-Mexico border and the Biden administration’s wide use of humanitarian parole programs to reduce chaos at the border. As a result of these grants of parole and other Biden administration moves, MPI estimates that, as of mid-2024, as many as 40 percent of unauthorized immigrants in the United States held a liminal (or “twilight”) status providing them temporary protection from deportation, such as Temporary Protected Status (TPS), Deferred Action for Childhood Arrivals (DACA), humanitarian parole, or pending asylum application.

As the size of the unauthorized immigrant population has increased since 2019, the share of immigrants who are from Central and South America has surged while the Mexican share has shrunk significantly. This trend reflects sharp increases in recent arrivals of Ecuadorians, Colombians, and especially Venezuelans, as well as steady growth in unauthorized arrivals from Guatemala and Honduras. 

These mid-2024 estimates, which derive from a unique MPI methodology, are based on the most recently available data from the U.S. Census Bureau’s American Community Survey (ACS). To incorporate improvements the Census Bureau has made in how it measures newly arrived immigrants and to correct for the historic undercounts of this population, MPI adjusted its methodology and revised upwards its estimates for 2021 through 2023. As a result, MPI’s revised estimate of the unauthorized population as of mid-2023 now stands at 14.7 million. 

Why the Sharp Increase in the Unauthorized Immigrant Population? 

For many years, MPI’s estimates of the overall unauthorized population hovered around 11 million, plus or minus a few hundred thousand (see Figure 1). This stability occurred because entries into the unauthorized population were continually offset by exits. For example, during the decade between 2010 and 2019, MPI estimates that roughly 6.1 million people crossed a border illegally or overstayed a visa, while 5.7 million unauthorized immigrants died, emigrated, or, less commonly, obtained legal status—resulting in a net increase of just 394,000 over that period. 

Between 2019 and 2024, MPI estimates the unauthorized immigrant population experienced a net growth of approximately 5 million people, or an average of 8 percent per year. The increases were driven by the uncommonly strong U.S. economic recovery after the COVID-19 pandemic as well as the large-scale displacement from countries throughout the Americas fueled by gang violence, political repression, and economic challenges.1 As a result, irregular arrivals at the U.S.-Mexico border surged in fiscal year (FY) 2021 and peaked in FY 2023, bringing a rising mix of nationalities from across the Western Hemisphere and beyond, before dropping slightly in FY 2024. For instance, Venezuelan irregular arrivals started to grow quickly following the severe economic and political turbulence that began in Venezuela in 2015 and has continued. Likewise, irregular migration from Honduras and Guatemala grew rapidly starting in 2019, including large shares of families, due to political instability and spells of agricultural stress that compounded the countries’ economic challenges. Irregular migration from Ecuador and Colombia also grew, due to episodes of insecurity and violence.

Increases were also driven by Biden administration policies that allowed most border migrants who reached U.S. soil to stay in the United States pending the outcome of removal proceedings in immigration court. Growth was further driven by the creation of new humanitarian parole programs that allowed legal entry and temporary stay for migrants from Afghanistan, Ukraine, Cuba, Haiti, Nicaragua, and Venezuela, as well as those from all around the world who reached northern Mexico and made appointments via the CBP One app to be screened for entry. And growth also came from sizable numbers of Europeans and others who overstayed their temporary visa.

The largest post-pandemic increase in the unauthorized immigrant population occurred between 2022 and 2023, with a growth of about 1.6 million. The annual growth between 2023 and 2024 slowed but was still significant at 1.1 million. 

The Growing Diversification in Origins

Although Mexico continues to be the top origin country, MPI’s analysis reveals the Mexican share of the unauthorized population has dropped dramatically—from being the overwhelming share in the 1980s and 1990s, to 62 percent in 2010 and 35 percent as of 2024. This has occurred as sizeable shifts in migration patterns, primarily from Central and South America, have reshaped the nationality makeup of the overall U.S. unauthorized immigrant population. 

Between 2019 and 2024, the unauthorized immigrant population from Central America increased by 2.3 million (see Table 1), a change driven primarily by migration from Honduras and Guatemala (see Table 2). The South American population increased by 1.3 million over the same period, primarily due to large-scale migration from Venezuela, Colombia, Ecuador, and Brazil. These increases far outpaced the net growth in the unauthorized population from Mexico, which rose by just 266,000 between 2019 and 2024. 

Table 1. Unauthorized Immigrants in the United States from Mexico and by Region, 2019 and 2024

After Mexico, the top countries of origin of the unauthorized immigrant population ranged from those in nearby northern Central America to South America, as well as the Philippines (see Table 2).

Table 2. Top Ten Countries of Origin for the U.S. Unauthorized Immigrant Population, 2019 and 2024

The Central American share of the unauthorized immigrant population increased from 15 percent to 27 percent between 2010 and 2024 (see Figure 2), even as Mexico for the first time fell below 50 percent in 2019. Notably, the share from South America doubled to 14 percent over this period, while the share from the Caribbean doubled to 6 percent. Except for Asia, where the share held steady over the 2010-24 period, the proportion of immigrants from other world regions also grew, even if by small margins. 

Continued Growth of a Twilight Population

In 2024, a rising number of people counted in the MPI estimates held some kind of temporary legal protection offering them short-term relief from deportation and access to work authorization. Many of them have subsequently lost their status, though, given Trump administration actions to terminate TPS programs, rescind humanitarian parole status from several groups, and deny certain asylum applications.

MPI has long counted asylum applicants and holders of DACA or TPS in its estimates of the unauthorized population, as have other demographers, and now also includes people with humanitarian parole. While the term “unauthorized” is an imperfect descriptor for noncitizens whom the U.S. government has granted the right of temporary stay, MPI includes these populations given their lack of a visa or other durable legal status, as well as the impermanence of statuses that could be revoked.

In early 2023, the Biden administration created two new humanitarian parole processes: a program permitting Cubans, Haitians, Nicaraguans, and Venezuelans (CHNV) with U.S. sponsors to fly to the United States at their own cost, and a process for migrants from all over the world to schedule an appointment at a port of entry through the CBP One app. These parolees, just like the Afghans who came mostly in 2021 and the Ukrainians who came through the Uniting for Ukraine program, were generally granted two years of work authorization and protection from deportation. 

Given that many people hold multiple forms of twilight status at once, it is difficult to know exactly how many of the 15.8 million unauthorized immigrants in 2024 had one or more temporary protections. However, drawing on administrative data, MPI analysts estimated that a maximum of 6.3 million people—or 40 percent of the overall unauthorized population—held a liminal status in mid-2024 (see Table 3). Due to overlap (for example parolees who applied for TPS, asylum, or both), the number and share was probably substantially lower.

Table 3. Maximum Number of Individuals Holding a Liminal Immigration Status, 2024

A Decrease on the Horizon? 

Unauthorized arrivals at the U.S.-Mexico border fell significantly from 2023 to 2024 as result of heightened levels of Mexican enforcement and a series of Biden administration asylum restrictions, slowing down the growth in the unauthorized immigrant population during that period.2

It is likely that the unauthorized immigrant population decreased or stayed relatively constant in 2025. The Trump administration inherited a quieter U.S.-Mexico border and implemented strict policies that further decreased irregular border arrivals to levels not seen since the 1970s.3 It also ended the Biden administration’s large-scale humanitarian parole programs and has implemented a whole-of-government push to prioritize deportations of already present unauthorized immigrants and turn up the pressure on individuals to “self deport.”4

Whether the Trump administration can meet its goal of deporting 1 million people a year remains to be seen, given the fact deportations require extensive resources and collaboration with other governments. Though millions have lost their temporary protection against deportation, most still have a right to an immigration court hearing, which can slow removals, and some may qualify for asylum or other form of protection. Meanwhile, the administration continues to build the enforcement and detention infrastructure necessary to increase deportations from the U.S. interior.

Should the administration succeed in its efforts to sizably ramp up deportations and if border entries remain at their remarkably low levels, the unauthorized immigrant population may begin to decrease into 2026 and beyond.