Abstract
This paper examines how environmental heterogeneity influences the formation of close-knit communities. I provide support for the social learning hypothesis, which posits that diverse environmental conditions limited American farmers’ ability to learn from neighbors, weakening communal ties. I document a negative county-level association between soil heterogeneity and close-knit communities. Using individual-level data on nineteenth-century domestic migrants, I show that this association is not driven by selective in-migration and document farmers’ cultural adaptation using a difference-in-differences framework. Focusing on mechanisms, I show that soil heterogeneity slowed farmers’ agricultural learning and prompted those who depended on social networks to migrate elsewhere.