Spain's development from a premodern society into a modern unified nation-state with an integrated economy was painfully slow and varied widely by region. Economic historians have long argued that high internal transportation costs limited domestic market integration, while at the same time the Castilian capital city of Madrid drew resources from surrounding Spanish regions as it pursued its quest for centralization. According to this view, powerful Madrid thwarted trade over large geographic distances by destroying an integrated network of manufacturing towns in the Spanish...