We study the causal relationship between geographic connectedness and development using one of the earliest massive trade expansions: the first systematic crossing of open seas in the Mediterranean during the time of the Phoenicians. We construct a geography-based measure of connectedness along the shores of the sea. We relate connectedness to economic activity, which we measure using the presence of archaeological sites. We find an association between better-connected locations and archaeological sites during the Iron Age, at a time when sailors began to cross open water routinely on a large scale. We corroborate these findings at the world level.

Africa?s demand for urban housing is soaring, even as it faces a proliferation of slums. In this setting, can modest infrastructure investments in greenfield areas where people subsequently build their own houses facilitate long-run neighborhood development? We study Sites and Services projects implemented in seven Tanzanian cities during the 1970s and 1980s, and we use a spatial regression discontinuity design to compare greenfield areas that were treated (de novo) with nearby greenfield areas that were not. We find that by the 2010s, de novo areas developed into neighborhoods with larger, more regularly laid-out buildings and better-quality housing.