This study explores the consequences and origins of between-ethnicity economic inequality across countries. First, combining satellite images of nighttime luminosity with the historical homelands of ethnolinguistic groups we construct measures of ethnic inequality for a large sample of countries. We also compile proxies of overall spatial inequality and regional inequality across administrative units. Second, we uncover a strong negative association between ethnic inequality and contemporary comparative development; the correlation is also present when we condition on regional inequality, which is itself related to under-development. Third, we investigate the roots of ethnic inequality and establish that differences in geographic endowments across ethnic homelands explain a sizable fraction of the observed variation in economic disparities across groups. Fourth, we show that ethnic-specific inequality in geographic endowments is also linked to under-development.

We investigate whether political jurisdictions form in response to the trade‐off between economies of scale and the costs of a heterogeneous population. We consider heterogeneity in income, race, ethnicity, and religion, and we test the model using American school districts, school attendance areas, municipalities, and special districts. We find strong evidence of a trade‐off between economies of scale and racial heterogeneity; we also find evidence of a trade‐off between economies of scale and income heterogeneity. Conversely, we find little evidence that ethnic or religious heterogeneity shapes jurisdictions. To clarify the direction of causality between heterogeneity and jurisdictions, we exploit shocks to racial heterogeneity generated by the two world wars.