From his first days in office, U.S. President Joe Biden has had to contend with a surge in migration across the U.S.-Mexican border, in particular from the “Northern Triangle” countries of Guatemala, Honduras, and El Salvador. Instead of building walls or beefing up border security, as his predecessor did, Biden has promoted an ambitious $4 billion plan to address what he has called the “root causes” of irregular migration. By tackling insecurity, corruption, and poverty in Latin America, the Biden administration is betting that it can persuade many would-be migrants who lack visas to stay home.

Biden’s plan won’t slow the traffic at the U.S. border overnight, but it may help stabilize the flow over time, preventing the kinds of extreme surges of irregular migration that occurred at the beginning of this year. For the plan to work, however, Biden and his team must understand that migration pressures from the Northern Triangle follow two starkly different patterns: long waves that last decades and short spikes that last months.

The former, perhaps paradoxically, are symptoms of rising prosperity in the countries from which migrants hail, whereas the latter stem from crises and shocks. Any successful agenda focusing on root causes must distinguish between these two patterns of migratory pressure—encouraging the economic gains that drive long-wave migration while preventing the kinds of emergencies that drive short-wave surges. 


Emigration from poor countries to rich ones is rarely constant over time. Rather, it tends to happen in decades-long waves, often with clear beginnings and ends. These waves generally arise not from poverty but rather from growing wealth. As contradictory as it sounds, emigration from low-income countries usually increases as these countries get richer and more of their citizens have the means and the desire to travel abroad. Put another way, an important root cause of long-wave migration pressure is prosperity itself.

Take Sweden. Between 1860 and 1910, roughly one-fifth of the country’s population emigrated, mostly to the United States and Canada. This was not a time of economic collapse in Sweden. Just the opposite: its real income per capita doubled during this period. More recently, the long waves of migration from Mexico and South Korea that began in the mid-1970s came at a time when real incomes were rising rapidly in both countries, enabling their entry into the Organization for Economic Cooperation and Development by the 1990s.

Now it is Central America’s turn. Over the last decade, development gains in the region have enabled a long wave of migration to the United States and Mexico that appears to have just reached its peak. In all three Northern Triangle countries, richer and more educated people have shown a greater tendency to emigrate than poorer and less educated ones. The parts of the Northern Triangle with the least poverty have the highest rates of child migration to the United States. And many foreign aid programs, including those that brought more schooling to Honduran children and better nutrition to Guatemalan children, have been found to accelerate emigration years later.

An important root cause of long-wave migration pressure is prosperity itself.

How does development lead to migration? More disposable income means more money to pay for passage. Education and urbanization raise aspirations for a better life. And prior migration both inspires and facilitates subsequent migration. But perhaps the clearest way that rising wealth drives migration is through demographic change. In the poorest countries, high child mortality rates encourage parents to have numerous children. As countries emerge from poverty, child mortality rates quickly plummet, but fertility rates often do not. It can take up to a generation before parents feel comfortable having fewer children, meaning that there is often a surge of young people into the labor force a decade or two after countries begin climbing to middle-income status: the cohort of still numerous children who have survived into adulthood. Such youth bulges raise competition for jobs, land, and other resources among the young—who are the most mobile—even as prosperity soars.

This is exactly what has happened in the Northern Triangle over the last ten years. Between 2013 and 2018, youth entry into the labor force crested in all three countries, pushing many young people to look for opportunities abroad. That surge is finally starting to recede, mirroring the drop in fertility rates that occurred 15 to 25 years ago. In 2017, the number of Salvadorans between the ages of 15 and 29 stopped growing, and it has been shrinking ever since. Honduras’s youth cohort will stop growing five years from now. In Guatemala, annual growth of the youth cohort is on track to fall from almost 100,000 people per year to under 20,000 over the next nine years.

These demographic trends suggest that long-term migration from the Northern Triangle will fall over the next decade, as was the case in Mexico after the year 2000. The three million people from the Northern Triangle already in the United States will continue to reduce the cost and risk of further migration for years to come by helping those that follow in their footsteps. But the demographic surge that fueled record levels of migration over the last decade will come to a gradual end—the inevitable result of the Northern Triangle countries’ expansion of education, rising income levels, and falling fertility rates.

The root causes of this type of migration are therefore best thought of not as threats to be addressed but as successes to be welcomed. A gradual rise in living standards, education, health, and purchasing power across the region is clearly in the long-term interests of the United States.


Unlike long waves, short spikes of migration are nothing to celebrate. They are brief and intense, typically lasting only a few months, and they put migrants and their families at tremendous risk. The spikes that occurred in May 2019 and March 2021 caused the monthly number of arrests at the U.S.-Mexican border to surge to four times the typical level, burdening U.S. law enforcement and stoking popular fears about a crisis at the border.

These sudden migratory surges arise not from prosperity but from shocks in Latin America, magnified by feedback from migrants’ social networks and from opportunistic smugglers encouraging people to emigrate. Heat waves, bad rainfall, natural disasters, and outbreaks of violence force people to flee both direct threats to their lives and indirect threats to their livelihoods. Erratic swings in U.S. policy also contribute to short migration spikes: a sudden tightening of border restrictions can produce pent-up demand to cross, while a sudden easing of restrictions can help smugglers convince migrants to try their luck.

Unlike the drivers of long-wave migration, however, many of the root causes of these short spikes can be directly addressed by U.S. policy. Risk and instability, not a generalized lack of opportunity, give rise to these sudden surges. The United States can therefore alleviate short-spike pressures by helping reduce the risk of weather shocks, food insecurity, and gang violence in Northern Triangle countries, whether through cooperating with governments in the region, directly assisting civil society, or partnering with international agencies and the private sector.

So far, the Biden administration has indicated that it will deploy aid in this manner. In addition to addressing “longstanding issues” such as corruption and poverty, its twofold migration strategy will aim to protect people in the Northern Triangle from “acute factors” for migration such as hurricanes, drought, and the COVID-19 pandemic. And while the focus on long-standing issues is unlikely to alleviate long-wave migration pressures, the emphasis on acute ones has a real chance to reduce short-spike migration pressures in the near term.

Risk and instability, not a generalized lack of opportunity, give rise to sudden surges of migration.

But perhaps the most effective way to address pressure for irregular migration—whether in short spikes or long waves—has been the least discussed in Washington: creating predictable, legal migration channels from the Northern Triangle. Whereas Mexicans have long enjoyed access to seasonal work visas to the United States, most citizens of Northern Triangle countries who lack university degrees or immediate family members who are U.S. citizens must either cross illegally into the United States or apply for asylum at the border.

The reason is that U.S. employers, not the U.S. government, get to determine the nationality of seasonal workers under the United States’ only sizable employment-based visa program for jobs that do not require a bachelor’s degree. Washington merely accepts or rejects visa requests from employers. As a result, no one in Honduras, for example, can get a seasonal work visa unless a U.S. company specifically requests Hondurans.

Biden has promised to “enhance access for individuals from the Northern Triangle to visa programs,” as an executive order from February decreed, but doing so will require speaking directly to U.S. employers of seasonal workers to address any concerns they might have about recruiting in the Northern Triangle. The Biden administration should also work with international organizations such as the World Bank and the International Organization for Migration to build employers’ trust in the region’s workforce. And to offset the modest additional cost of recruiting in the Northern Triangle, the U.S. government could offer incentives, such as temporary waivers of visa fees, to employers willing to hire from the region.    

The Biden administration should also assist Northern Triangle countries in building transparent, ethical recruiting systems free of the fraud and abuse that plague unregulated recruitment in some countries, often violating workers’ basic rights. This can certainly be done. U.S. and other Western aid agencies have helped to build excellent systems for recruiting seasonal workers from poor countries around the world.

Finally, the Biden administration will need to institutionalize this system of recruitment from Northern Triangle countries. Currently, no federal office or entity has a permanent mandate to facilitate access to U.S. visas for citizens of any particular country. Unless such an office is created, efforts to expand visa access to Northern Triangle countries will risk getting bogged down in the federal bureaucracy, where different agencies often have conflicting mandates and no single actor is accountable for delivering results.


Biden’s “root causes” agenda is ambitious, but not impossible to achieve if his administration builds into its strategy the vital distinction between long-wave and short-spike migration. His administration is right to pursue long-term investments in the Northern Triangle, fighting corruption, improving education, and attracting foreign capital. These worthy goals will serve the interests of the United States for generations to come.

But long-term development assistance will not address the root causes of destabilizing short-term spikes (and in the near term, fostering economic growth may actually increase long-wave migration pressures). To prevent sudden short-term spikes, the Biden administration must focus on reducing the risks faced by families in the Northern Triangle. It should help countries in the region forestall preventable crises such as food insecurity or outbreaks of violence. And it should work to mitigate the consequences of those crises that can’t be avoided, whether through insurance schemes or emergency relief in the wake of natural disasters.

The Biden administration is off to a promising start when it comes to addressing the root causes of irregular migration, particularly that which occurs in short spikes. But a major root cause of short- and long-wave irregular migration is not in Latin America but in the United States itself: the acute lack of regular channels for migration from the Northern Triangle. Until this root cause is addressed, it will only be a matter of time until the next short spike.

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