Migration across national borders might sometimes seem like water behind a dam–a pent-up force waiting to break loose unless restrained by a physical or legal wall. But look a little closer, and episodes of large-scale migration are often driven by fundamental factors like differences in birthrates and economic prospects, as well as by past historical and political ties. Gordon Hanson and Craig McIntosh make this point in their essay \”Is the Mediterranean the New Rio Grande? US and EU Immigration Pressures in the Long Run,\” which appears in the just-published Fall 2016 issue of the Journal of Economic Perspectives.
\”The tens of thousands of migrants streaming into Europe during late 2015 and early 2016 created an indelible image of how humanitarian crises—in this case associated with the Syrian civil war—propel international migration. Although political instability in the Levant may have kicked migration to Europe into a higher gear, immigration flows to the continent in the medium- and long-run are likely to be sustained by sharp differentials in labor-supply growth between regions to the north and to the south of the Mediterranean Sea. The present European migration scene is the latest act in a long-running global drama in which cross-country differences in population growth, abetted by disparities in aggregate labor productivity, create pressures for international migration. Periodically, economic or political crises unleash these pressures and generate sustained flows.
\”During the last quarter of the 20th century, the principal actors in this global drama were Mexico and the United States. The US baby boom came to an abrupt halt in the early 1960s, causing growth in native-born labor supply to slow sharply two decades hence, once the baby-boom generation had fully reached working age. In Mexico, birth rates declined much later. High fertility in the 1960s—when Mexico’s fertility rate (the number of births per woman of childbearing age) averaged 6.8, versus 3.0 in the United States—meant that Mexico’s labor force was expanding rapidly in the early 1980s, just as a severe financial crisis hit. This crisis, and the decade and a half of economic instability that ensued, unleashed a great wave of Mexican migration to the United States. Encouraging this flow was steady US economic growth during the “Great Moderation” period from the mid-1980s up through 2007. In a pattern common to migration events stretching back into human history, early migrants eased the transition for later arrivals by offering advice on how to find jobs and housing, opening familiar stores and restaurants, and creating enclaves in which Spanish was spoken alongside English.
\”The Mexican migration wave to the United States has now crested. Fertility rates in Mexico, at 2.3 births per woman of childbearing age, are only modestly above those in the United States, at 1.9. Labor-supply growth in the two countries is projected to be roughly the same in coming decades. Although living standards in Mexico remain well below US levels, Mexico has tamed the macroeconomic volatility it experienced during the 1980s and 1990s. Net US immigration from Mexico plunged after the onset of the Great Recession in 2007 and has been slightly negative every year since. Absent a significant new economic or political crisis in Mexico, or unexpectedly robust US economic growth, it is unlikely that Mexico-to-US migration rates will again reach the levels witnessed between the early 1980s and the mid-2000s.
\”The European immigration context today looks much like the United States did three decades ago. In Europe, which long ago made its demographic transition to low birth rates, declines in fertility in the 1970s and 1980s set the stage for a situation in which the number of working-age residents is in absolute decline. Countries in the North Africa and Middle East region, in contrast, have had continued high fertility, creating bulging populations of young people looking for gainful employment in labor markets plagued by low wages and the scarcity of steady work. Further to the south, population growth rates in sub-Saharan Africa, a region with still lower relative earnings, remain among the highest in the world. Many countries in North Africa and the Middle East are in a period of profound political and economic upheaval. Migrants escaping military conflict in Afghanistan, Iraq, Libya, and Syria are crossing the Straits of Gibraltar, the land and sea borders that divide Turkey and Greece, and the narrow Mediterranean passage that separates northern Libya and southern Italy. Further to the south, conflicts in Chad, Eritrea, Mali, and Nigeria are also generating labor outflows. These new triggers are being tripped in a demographic environment that is ideal for perpetuating emigration well into the future. As further motivation, established populations of Algerians in France, Moroccans in Spain, the Turkish in Germany, and sub-Saharan Africans in Italy may offer support and solace to the new arrivals as they settle in.\”
\”Motive and opportunity, however, are far from sufficient conditions for migration to occur. The United States and Mexico, which share a 2,000-mile land border, have long had widely divergent incomes. In 1960, per capita GDP (PPP adjusted) in the United States was triple that in Mexico, a ratio that remained essentially unchanged during the following two decades—yet there was only a modest migration response. As a share of Mexico’s national population, the number of the Mexicans living in the United States stood at 1.5 percent in 1960 and 3.2 percent 20 years later. In 1980, immigrants from Mexico accounted for just 1.0 percent of the US population. What sparked substantial labor flows from Mexico to the United States was the onset of the Mexican debt crisis of the 1980s and the “lost decade” of economic stagnation that followed. Between 1982 and 2000, the ratio of US-to-Mexico per capita GDP rose by over one-and-a-half times, from 2.3 to 3.8. …
\”Equally impressive is that a single source country, Mexico, accounts for just under one-third of US working-age immigrants. The 10.2 million individuals born in Mexico and living in the United States accounted for fully 13.0 percent of all immigrants living in an OECD country in 2010. Remarkably for a country as large as Mexico, these immigrants were equal in number to 13.5 percent of Mexico’s working-age population. Indeed, the Mexico-to-US migrant flow is one of the largest international migration episodes that the world has seen.\”
\”As an example, we predict the number of African-born first-generation migrants aged 15 to 64 outside of sub-Saharan Africa to grow from 4.6 million to 13.4 million between 2010 and 2050. During this same period, the number of working-age adults born in the region will expand from under half a billion to more than 1.3 billion, meaning that international migration would only absorb 1 percent of the overall population growth. Given an African continent expected to contain almost four billion people by 2100, the presence or absence of a migration safety valve would have profound implications. The coming half century will see absolute population growth in sub-Saharan Africa five times as large as Latin America’s growth over the past half century. Even with our predictions for expanded population pressures to certain countries of Europe, which are likely to be perceived as very high levels of immigration by those countries, Europe would be absorbing only a small share of Africa’s projected population increase.\”