Mayan towns in the Guatemalan highlands hold markets on specific days of the week. A market is attended by local townspeople, by peasants residing in the town’s hinterland, and by vendors bringing wares from other towns. A market functions to bring in goods from other ecological zones, to...

Positive autocorrelation implies that proximate observations take on similar values. “Proximate” can be defined in many different dimensions. In a cross-section of U.S. regions, it can be defined using physical distance, cultural similarity, ecological similarity, or using frequency and...