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It Is Too Simple to Call 2021 a Record Year for Migration at the U.S.-Mexico Border
U.S. Border Patrol agents prepare to process migrant encountered near Arizona
Jerry Glaser/U.S. Customs and Border Protection

With today’s news that U.S. Customs and Border Protection (CBP) encountered migrants crossing the U.S.-Mexico border without authorization 1.66 million times in fiscal year (FY) 2021 (a number that rises to 1.73 million when interactions at ports of entry are included), much is being made of the fact that these numbers top the 1.64 million apprehensions that occurred in FY 2000, making this the highest year on record. While there is no doubt that 2021 represents a high one for border arrivals—reflecting both an increase from recent years and diversification of nationalities—this does not necessarily mean that more migrants were intercepted or illicitly entered the country than was the case 21 years ago.

The determination of which year represents the record year is not clear cut and is complicated by a number of factors, not least that there is no measurement of unique individuals apprehended in the 1990s and early 2000s. Apprehensions represent events, not individuals, and it has only been in recent years that the Department of Homeland Security (DHS) has begun tracking enforcement activities by the number of unique individuals intercepted, making an apples-to-apples comparison with 2000 unfeasible.

Both 2000 and 2021 were marked by a high rate of recidivism—in other words, migrants who had been encountered and turned back by the Border Patrol trying to cross again (and sometimes multiple times). This means that, in both years, far fewer than 1.7 million unique individuals crossed the border without authorization (see section on recidivism for further discussion). Further, the number of migrants who were able to successfully enter the United States unlawfully without being apprehended was significantly higher in FY 2000 than now—a metric Border Patrol encounter reporting does not address.

More than 2.1 million unauthorized migrants would have crossed into the United States without being apprehended in FY 2000, based on that year’s estimated 43 percent apprehension rate. Official data have not been released on the number of unauthorized migrants who avoided apprehension in FY 2021. But media reports of Border Patrol numbers cite a figure of 400,000 “got-aways” (those detected but not intercepted by the Border Patrol) for FY 2021. Got-aways represented 74 percent of estimated successful unlawful entries in FY 2018. If that trend has held and the got-away numbers cited for 2021 are accurate, there were about 540,000 successful unlawful entries in FY 2021—less than one-fourth the estimated 2000 total.

Different Times, Different Flows

Today’s flows are far different than they were 20 years ago. Then, illegal crossers were overwhelmingly single Mexican men seeking work in the United States and trying to evade Border Patrol detection. Today’s migration is increasingly made up of Central American families and unaccompanied children who are turning themselves in to border agents, often requesting asylum. Further, the number of Border Patrol agents at the southwest border almost doubled from FY 2000 to FY 2020, rising from 8,580 to 16,878, and the agency’s use of technology to detect crossings has increased. These factors have greatly reduced the share of migrants who enter the United States illicitly.

Comparing the numbers of migrants who were intercepted this past year with earlier periods is further complicated because present-day enforcement reporting now goes beyond counting apprehensions (the term for those taken into custody and processed under U.S. immigration law) to also include expulsions under the Title 42 March 2020 public health order, still in place today, which allows for migrants caught crossing without authorization to be immediately expelled to Mexico or their home country. Apprehensions and expulsions together make up “encounters,” in Border Patrol parlance.

Of the 1.66 million migrants encountered in FY 2021, about two-thirds of all encounters by the Border Patrol between ports of entry resulted in migrants being immediately expelled. The remaining one-third resulted in migrants being detained or released inside the United States.

Figure 1. U.S. Border Patrol Southwest Border Encounters between Ports of Entry Resulting in Apprehensions or Expulsions, FYs 2000-21

Notes: Apprehensions refers to encounters that resulted in migrants being processed for removal or return under U.S. immigration law. Expulsions refers to encounters that resulted in migrants being immediately expelled to Mexico or their country of origin under the Centers for Disease Control and Prevention’s Title 42 pandemic-era public-health order. Apprehensions and expulsions together equal the total number of encounters.
Sources: U.S. Border Patrol, “United States Border Patrol Southwest Border Sectors: Total Encounters By Fiscal Year (Oct. 1st through Sept. 30th),” accessed October 12, 2021, available online; CBP, “Southwest Land Border Encounters,” updated October 22, 2021, available online.

Recidivism Rates

High levels of repeat crossings in both 2000 and 2021 also account for the number of individual migrants intercepted crossing the border being considerably lower than the total number of encounters. While recidivism rates, which measure repeat crossings, were first calculated beginning in FY 2005, the rate that year of 25-31 percent is likely close to what was experienced in FY 2000. The present-day rate could be higher: from May through September (the only months when a 2021 rate was officially reported) it ranged between 25-38 percent. There has always been some level of recidivism, but it had been in significant decline as the Border Patrol changed its enforcement strategy beginning in 2011, reaching a low of 7 percent in FY 2019, before surging since imposition of the public health order in March 2020.

While CBP did not provide the precise number of unique individuals encountered at the southwest border for all of FY 2021, its monthly totals add up to about 1.1 million people, the vast majority crossing without authorization. Though the perception may be that unauthorized crossings are occurring at a pace unseen before, during the most recent period of high crossings, there were 851,513 unique individual encounters in the first 11 months of FY 2019 (no full-year data were reported). This suggests that the real increase in individuals caught crossing the border from FY 2019 to FY 2021 is noteworthy, but more gradual than today’s reporting of Border Patrol data might initially suggest.

Causes of Increased Migration

Even though the overall FY 2021 numbers may not rival the FY 2000 numbers for first-time encounters of migrants and for actual illicit entries, they do represent a significant uptick in activity at the border in comparison to recent years. One key reason for this increase is the pandemic-generated economic decline experienced throughout Latin America, which sparked increased poverty, unemployment, and food insecurity, thus motivating people to move north in search of better opportunities. Two other key reasons involve U.S. border management policies adopted amid the pandemic and their effects on different populations.

FY 2021 saw the highest level of encounters of single adult migrants in at least ten years. More so than with other categories of migrants, a portion of this increase can be attributed to recidivism. In the mid-2000s, DHS had begun to tackle the high rates of repeat crossings by steadily increasing its use of formal deportation and similar consequences for apprehended migrants—most of them single adults from Mexico—rather than voluntary return to Mexico, as had been typical until then. These consequences, which also included referring migrants for criminal prosecution, could be escalated if individuals tried to cross again after their initial apprehension. This strategy—combined with the 2008-09 recession in the United States and job growth in Mexico—succeeded in reducing apprehensions of Mexicans to 128,000 in FY 2017, from the 1.6 million peak in FY 2000.

Under the pandemic expulsions policy, these consequences have, for the most part, been lifted. Expelled migrants are not formally processed for removal, so there are no penalties for subsequent crossing attempts. Instead, the Border Patrol’s enforcement strategy approximates the voluntary return policy for single Mexican adults that existed earlier, and extends, for the first time, to Central American adults as well. The difference is that the United States has now demonstrated it can implement effective consequences—it is choosing not to use them.

Diversification of Encounters

The FY 2021 increase is also due to the diversification of arriving flows, which are increasingly composed of families and unaccompanied children from Central America, as well as migrants of other nationalities. Migration of these groups has grown over the past decade. Families and unaccompanied children made up just 10 percent of all apprehensions in FY 2012. They reached a high of 65 percent in FY 2019. That share dropped to 36 percent in FY 2021 due to increased encounters of adult repeat crossers. Similarly, migrants from countries other than Mexico, El Salvador, Guatemala, and Honduras increased from 1 percent of total apprehensions in FY 2008 to 22 percent in FY 2021.

It has historically been easier for these groups to enter the United States to seek relief, as consequences at the border may not apply to them or may be more difficult to apply, leading to periodic spikes in their migration. And during the pandemic, none of these groups has been expelled at the same rate as single adults and migrants from Mexico, El Salvador, Guatemala, and Honduras.

This uneven enforcement framework (combined with push factors from pandemic-affected economies) may have caused potential migrants to try their luck crossing the border, given the likelihood they would be able to enter the United States. Encounters of migrants of other nationalities thus rose significantly this past year from a previous high in FY 2019, as did encounters of unaccompanied children. Meanwhile, the number of single adults, Mexicans, Salvadorans, Guatemalans, and Hondurans processed under U.S. immigration law, rather than expelled under the public health order, decreased.

Figure 2. U.S. Border Patrol Southwest Border Encounters Resulting in Apprehensions vs. Expulsions for Different Populations, FYs 2019 and 2021

Notes: There is overlap between counts of apprehensions/encounters by nationality and by demography.
Sources: CBP, “Southwest Land Border Encounters”; CBP, “U.S. Border Patrol Southwest Border Apprehensions by Sector Fiscal Year 2019,” updated November 14, 2019, available online.


In comparing the two years, the number of unique individuals crossing the U.S.-Mexico border in FY 2021 was likely smaller than in FY 2000. At the same time, 2021 border encounters represent an important increase from recent years, even if more gradual than some reports suggest.

Pandemic-era policies resurrected issues that had been effectively addressed in the immigration system—repeat crossings of single adults—and cast a harsh light on long-neglected ones: the lack of border management strategies to deal with families, unaccompanied children, and migrants from countries other than Mexico and the northern countries of Central America.

While the high number of border encounters this past year should not be viewed as eclipsing the migration levels of the early 2000s, current strategies—especially the expulsions policy—have faltered in providing procedural guarantees for protection as well as in deterring potential migrants from crossing. This should catalyze changes in border enforcement that recognize the changing realities of current and possible future flows, as well as development of more robust, urgent regional cooperation measures that look beyond the border in addressing unauthorized migration.