The increasing arrival of people from different origins in high-income countries raises the issue of the coexistence and the exchange of different norms and ideas that affect productivity. This article documents the impact of immigrant birthplace diversity on workers’ wages at both metropolitan overall and sector-occupation population levels using US data between 2000 and 2019. This granular approach exploits the skill similarities and the high levels of interaction of workers from those groups to disentangle the diversity effects from general skill heterogeneity related to national specialisations. Finally, It exploits the rich compositions of the 21st century’s migration flows to take cultural and economic distances into account. The results suggest that metropolitan immigrant diversity of workers from the same sectors and occupations is positively related to their wages. It also provides evidence of a local positive effect of migrant diversity in local groups with similar experience and education that captures these complementarities. The gains are maximised when immigrant birthplace diversity in a local occupation is the result of migrations from countries close economically and culturally to the US population, and from culturally distant countries for diversity at the level of workers similar in education and experience. These results are mostly driven by workers without college education.

 This research examines the path-dependence relationship between political and economic integration in Western Europe under Roman rule and economic linkages between the current European regions, to investigate whether the Roman trade integration survived time and its numerous technological and political shocks. Based on gravity models that allow the role of several geographical factors to be excluded from the estimates, it provides empirical evidence that European NUTS2 regions that were highly integrated economically and politically under the Roman Empire still traded more in the early 21st century. Part of this effect is explained by the current road network that is partially following the old networks, but a sizeable part is also attributable to cultural convergence and local industrial specializations.

 The Economics of diversity (in the words of Ozgen (2021)) relates to a literature assessing the economic impact of birthplace or racial/ethnic diversity. It mostly contains studies at regional levels that are characterized by heterogeneous results associated with local contexts. The similarity of the models and instrumental strategies used in the literature provides fertile ground for a meta-analysis to formally analyze external validity and synthesize the impact of diversity on productivity and innovation at the regional level. In this (early stage) research, We built a new dataset by gathering relevant estimates and information from the universe of the available corresponding literature. We limited our scope to research considering birthplace diversity at a regional level and on a country scale. The main goal of the research is to estimate a Bayesian Hierarchical Model to average out study-specific variances to estimate the external validity of the results obtained based on local estimates.