The war declarations of August 1914 had far-reaching implications for modern long-distance international mass migration. For most of the preceding century, in the majority of big economies, the movement of people around the world had been largely peaceful, voluntary and propelled by market incentives. Since 1914, however, it has been mostly shaped by politically determined quotas and legal restrictions, or driven by flight from war, oppression or similarly fearsome dangers and disasters.

These changes in migration policies and patterns had happened before 1914, and were to happen again by warfare and economic upheaval in the 1920s, 30s and 40s. There had been significant refugee flows in the Franco-Prussian War and the Balkan wars of the late 19th and early 20th centuries. After the 1918 armistice, there was the Russian Civil War, ethnic cleansing in the near East and the rise of fascism, all of which sent millions more into flight. Nearly all migration from China to America had already been halted in the 1880s by ethnically explicit legal restrictions.

However, the events of August 1914 were a turning point. The demise of the world’s open borders was signalled as soon as the lights went out all over Europe. When the powers of sea and land were engaged in conflict, Britain and Germany’s transportation of the transatlantic core of global migration gave way to blockades, torpedoes and warships. Mass international labour migration, which had bolstered urban and industrial growth across the North Atlantic for decades, declined as millions of mobilized soldiers marched to war. At either end of the dominant European front, neutral Netherlands and Switzerland became prime migration corridors for unprecedented volumes of homebound expatriates and war refugees.

At Ellis Island, arrivals fell to their lowest levels in many decades, while returnees rushed to Europe in record numbers. The giant immigrant-carrying vessels of the North Atlantic commercial shipping lines were interned, impounded and/or converted to military use, and transatlantic passenger services were cut back. By 1915, voyages from Europe to the US had fallen by more than 70% from 1913 and steerage passenger arrivals had dropped by more than 90%.

A partial resurgence of transatlantic migration to the US after 1918 was short-lived because the war also significantly changed the American economy. Public opinion in the US also changed, with support for unrestricted international migration dwindling and opposition to it increasing. German-American voters – influential supporters of open borders before 1914 – were less politically active after 1917 when the US entered the war against the Kaiser. After the war, Americans viewed foreigners in general with greater suspicion. US businesses, meanwhile, had developed lasting alternatives to overseas immigration, relying more on migrants from Canada, Mexico and rural US states, on female employees and on increased machinery itself – which, it was pointed out, was not at risk of going on strike, moving to the next town or relocating back to Europe.

Cross-border labour migration resumed in Europe after 1918, but on a limited scale. The war precipitated by an “incident in the Balkans” had led to economic balkanization in central Europe. Sizeable refugee flows continued and the new League of Nations established the first High Commission for Refugees in 1921. In the 1920s, American laws changed. Limited qualitative exclusion of migration was permanently replaced by strict quantitative limits.

Global migration, overwhelmingly governed by labour markets and family networks before 1914, has not returned since. Today’s voluntary transnational migration might be sizeable, and co-evolve with business patterns and network feedbacks as before, but it does so under mostly restrictive policies rendered less predictable by the politics of “strange-bedfellow” coalitions. Free-market advocates and multicultural progressives seek the relaxation of border restrictions, while labour unions, nativists and environmental groups are more reluctant to see those controls attenuate. Multinational corporations are laboratories of legal alternatives to mass labour relocation, while undocumented migration tends to weaken the efficacy of quotas and restrictions, without undoing them.

As salient as the 1914 policy change undoubtedly was for the history of international migration, it should not obscure important influences running in the opposite direction. Because migrant workers are often close to the pulse of an economy, their movement can serve as a barometer for major social, economic and political trends.

Modern labour migration usually reflects the segment of the workforce in temporary and cyclical employment, and transport networks are usually attentive to hiring trends for those sorts of jobs. Transatlantic shipping line agents and analysts in the early 20th century, for example, often took the level of prepaid tickets as an indication of cyclical fluctuations, which their steerage business tended to reflect in magnified form. In the US recession of 1907-08 (the sharpest downturn of the decade prior to the First World War) factory production was about 20% lower than the previous year and employment fell roughly 10%, but net migration dropped by about 150% as a large net outflow of migrants returned to Europe. The abrupt curtailment of immigration in August 1914 and subsequent outpouring of repatriates and refugees, particularly from Belgium, were early signals that the new European war could to lead to a more radical economic disturbance than prior wars had.

In his famously prescient 1919 book, The Economic Consequences of the Peace, John Maynard Keynes described the open borders of the then bygone first age of globalization before WW1:

“The inhabitant of London could order by telephone, sipping his morning tea in bed, the various products of the whole earth, in such quantity as he might see fit, and reasonably expect their early delivery on his doorstep; he could at the same moment and by the same means adventure his wealth in the natural resources and new enterprises of any quarter of the world, [and] he could secure forthwith, if he wished it, cheap and comfortable means of transit to any country or climate without passport or other formality.”

A quarter of a century and another world war later, Keynes helped establish an institutional framework to gradually restore key components of the pre-1914 international free trade in goods, services and finance. Returning to free cross-border movement of labour has been more recent, limited and tentative, however. Today, there are powerful forces pushing migration hurdles lower, or aside – not least the ongoing information convergence in the “global village” – but opposing forces seem nearly as strong. Unlike goods and money, people are accompanied in their international travels by social, political and cultural baggage, and the act of their relocation transforms not just the places they settle in but the countries they come from.

Migration processes are often controversial, difficult to predict and dependent on fragile political compromises, especially in a world of considerable inequality.

By most indications, globalization in some form seems likely to persist for the foreseeable future, although the golden age of open borders described by Keynes does not look retrievable. Compared with their early 20th-century counterparts, early 21st-century societies face a quite different constellation of vulnerabilities with different resources and opportunities.

In the long arc of human history, half a millennium of demographic movement from Eurasia to the Americas was liable to be a one-off, regardless of geopolitics. But unfettered worldwide migration did not gradually phase out (as it had developed) over decades and centuries. To a considerable and lasting degree, it was lost following the guns of August 1914.

This article first appeared in voxeu.org.

Author: Drew Keeling is a historian interested in the mass migration across the North Atlantic

Image: Students pose for a photo with a globe during a campaign to mark World Earth Day in a middle school in Dexing, Jiangxi province. REUTERS/China Daily