A new study refutes a highly influential theory in migration economics: the ‘migration hump’, which states that when a country develops, migration goes up. Taking a closer look at the data at the country level and systematic difference between countries, two researchers from the Kiel Institute for the World Economy (IfW) show that rising incomes in poor countries actually reduce emigration. The political implications are far-reaching.

Throughout the past decades, the highest emigration rates have been observed in countries in an income range of $7,000 to 14,000, indicating a hump-shaped relationship between economic development and migration. Although merely based on cross-sectional evidence, the ‘migration hump’ is widely interpreted as a causal relationship. Therefore, economic progress in developing countries is assumed to increase migration.

With two-thirds of the world’s population living in countries below the $7,000 threshold, economic development in poor countries will – according to the concept of the migration hump – boost global emigration in the future. Effective development policy would thus raise immigration pressures, confronting policy-makers in destination countries with a sensitive trade-off between supporting development and reducing immigration pressures. 

Against this backdrop, the researchers revisited the relationship between economic development in low-income countries and migration to OECD destinations and investigated whether the migration hump holds up to more scrutiny. 

Correlation or causality

Yet, while this relationship is inherently intertemporal, present studies rely almost exclusively on cross-sectional evidence. The fact that middle-income countries experience higher emigration than their poorer counterparts might be a direct consequence of their income level or it might be due to fundamental differences between low and middle-income countries that simultaneously affect both development and emigration.

In the new study, the authors demonstrate that the migration hump is merely a cross-sectional phenomenon that is significantly driven by small outlier countries. Moreover, countries at the upwards-sloping part of the migration hump, on average, differ markedly from richer countries with respect to crucial exogenous factors such as distance to OECD countries, size and past colonial ties. These exogenous characteristics are well known to shape both development and migration.

Inferring rising emigration for today’s poor countries from higher emigration rates in middle-income countries might therefore be misleading.

The researchers compared the migration data for OECD countries from 198 third countries over a period of 35 years to development data for those countries to see if other factors – apart from GDP or development – play a role in peoples’ migration decisions. 

When poor countries become richer, emigration decreases

To account for these and other unobserved differences between countries the authors employ a panel set-up and investigate the relationship between economic development and emigration within countries overtime. 

By analysing countries’ evolution rather than comparing systematically different countries, Schneiderheinze and Benček identify a small, but robust negative relationship between economic growth and emigration: when a poor country’s income rises, emigration to OECD countries does not go up, but down. In stark contrast to the established view, these findings indicate that the migration hump’s causality is merely due to omitted variables at the country level. 

Beyond the scientific debate, any policy discussion about supporting development in poor countries and reducing immigration pressures has so far referred to the substantial policy trade-off implied by the migration hump. In light of these new findings, policy-makers should not be too concerned about such trade-off any more. 


Further information:

Kiel Working Paper ‘More development, less emigration to OECD countries—Identifying inconsistencies between cross-sectional and time-series estimates of the migration hump



Claas Schneiderheinze 

Mercator Dialogue on Asylum and Migration (MEDAM) 

Kiel Institute for the World Economy

Kiellinie 66 | 24105 Kiel, Germany

T +49 431 8814-249



Media Contact:

Melanie Radike

Mercator Dialogue on Asylum and Migration (MEDAM)
Kiel Institute for the World Economy

Kiellinie 66 | 24105 Kiel, Germany

T +49 431 8814-329