The persistence of geographical inequalities is an intriguing puzzle. Many explanations have been offered for why specific geographies flourish while other regions deteriorate.Some have highlighted the impact of natural constraints, like the limited availability of arable land,distance from the sea and the prevalence of disease. Others have stressed the importance of the impact of human capital spillover in neighbourhoods via local institutions, peer effects and the influence of role models.Recently many have focused on the need for spatial agglomeration to generate technological innovation and technology-driven growth.