Abstract
We examine a half-century of crop yield growth along an 800-mile transect in the U.S. Great Plains. The main contributors to growth were non-specific technical change +53%, irrigation +26%, fertilizer +13% and chemicals +10%. Environmental changes were small and had a minor impact. The wide range of agroclimatic conditions produced significant sub-regional deviations. Irrigation was important in the more arid and warmer areas of the west, while fertilizer and chemicals were more important in the humid east. Sensitivity to weather has increased in the rainfed regions of the east while it has decreased in irrigated regions of the west.