Guatemalan migrants deported from the United States wait to board a bus after arriving in Guatemala City on July 31. (Orlando Estrada/AFP/Getty Images)
Opinion writer

Here’s the surprising truth behind the fact that 250,000 Guatemalan migrants have been apprehended at the southern U.S. border since October 2018: The mass exodus reflects the tremendous social and economic progress that the Central American country has made in the past half-century.

Life is still hard for most people there, much harder than it is in the United States, so it’s understandable that Guatemala’s poverty and violence figure prominently in the usual explanations for the northbound movement.

Yet the necessary condition for mass migration is sustained population growth, enough to produce a critical mass of youthful would-be emigrants. Guatemala’s 2018 population of 17.2 million represents a quadrupling since 1960, according to the World Bank. The current median age is 22.5, vs. 38.2 in the United States.

And this resulted from vastly improved public-health conditions, which continued to get slowly better over the past five decades despite bloody military rule, civil war and official corruption.

Guatemala is experiencing a transition first seen in 19th-century Britain — and superbly explained by Paul Morland in his book about demography and political development, “The Human Tide.”

For most of human history before 1800, high death rates offset high birth rates, leading to stagnant population growth. Thanks to rising food production, urbanization and better hygiene, England’s death rate fell and its population boomed. It generated working-age people to spare, many of whom migrated — to North America, Australia or elsewhere.

In due course, the demographic transition spread from England to continental Europe — and beyond. Now Guatemala’s turn has arrived. In 1960, 1 in 7 babies died before their first birthday; in 2017, only 1 in 50. In 1960, life expectancy at birth was 46.7 years; in 2017, 73.6 years. Life expectancy for Guatemalan females, 76.5 years, is now about the same as for American males.

Some 200,000 young Guatemalans — many of whom might not have survived infancy in the recent past — enter the labor force annually. Labor-force growth helps explain why Guatemala’s economy has expanded over the past decade, with real output per capita up 12 percent, according to the World Bank. Guatemala’s growth doesn’t create jobs for all, though, hence the migratory pressure.

Guatemala’s demographic trajectory closely resembles that of the former No. 1 “sender” of migrants to the United States — Mexico — albeit on a smaller scale and with a time lag.

In the 20th century’s last two decades, Mexico’s rapidly improving infant mortality and life expectancy yielded a growing population whose median age hovered in the high teens and low 20s. Its economy grew but not quite fast enough to absorb all new workers.

Consequently, more than 9 million Mexicans moved to the United States between 1980 and 2010. Mexican migration to this country peaked in the early 2000s, however, and essentially ceased, on a net basis, not long thereafter. Between 2010 and 2017 the number of Mexicans in the United States fell, from 11.7 million to 11.2 million, according to the Pew Research Center .

Why did the seemingly endless stream run dry? Partly because Mexico stopped producing new people as fast as before; its birth rate, now nearing 2 children per woman, is down dramatically from 7 per woman in 1960.

Twenty-first-century Mexico’s worry is societal aging, as it is for England, the United States and so many other industrial countries that have completed the demographic transition to a low-birth-rate, low-death-rate, slow-growth future.

Eventually the same will happen in Guatemala. Childbearing per woman is about 2.9, and falling. The median age is still in the early 20s, but rising; in six years, it should hit 25, which was Mexico’s median age when its exodus peaked. (Demographic trends for Honduras and El Salvador closely resemble Guatemala’s.)

Policy and short-term events shape migrant flows, as well as long-term population trends. For Guatemala, these factors include a punishing drought and a 2015 U.S. federal court ruling making it easier for migrant families with children to seek asylum and stay in the United States.

If violence and poverty caused migration in some simplistic sense, however, there should be less of it. Guatemala’s homicide rate declined by more than half between 2009 and 2018, from 45 per 100,000 to 22.4, according to the World Bank and InSight Crime. Income inequality, though still high, has also improved over the past 30 years, as measured by World Bank statisticians.

Reports of Guatemalans selling or mortgaging land to pay human smugglers suggest that the distressed middle- and lower-middle class, not the poorest of the poor, predominate among the emigrants.

In Central America today, human beings are responding to circumstances and incentives as countless others, our own ancestors included, have done before.

President Trump’s demonization of them dishonors this common heritage and squanders U.S. moral capital; his attempted crackdown may stop some migration at the price of pushing the rest further into illicit channels. The Wall Street Journal reports that Trump’s threats to close the border spurred many Guatemalans to move while they still could.

Meanwhile, opening the border to demographically and economically driven migration — as well-intended suggestions by Democratic presidential candidates might do — would defy reality in a different, but also potentially destabilizing, way.

What’s needed is trade, investment and aid that helps Central America consolidate social progress and share the fruits more widely. And we need a lawful, humane process for screening and admitting would-be newcomers — while this wave of immigration, like previous ones, runs its course.

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