The economic history of a region is determined by a complicated interaction among geological, biological, technological, social, and economic forces. A vivid portrayal of this process is found in the recent history of the rural American South; the resulting interplay of economic and social movements has been displayed there with irony and violence. Beginning gradually in the late 1930s, the adoption of labor-saving technology increased rapidly through the late 1940s and early 1950s. In some cases, the diffusion of a new technique grew by more than 100 percent per annum. Greatly lowered physical labor coefficients of new techniques created relatively profitable investment opportunities by substituting capital-intensive, low-variable-cost methods for labor-intensive, high-variable-cost methods of production. A similar process was also at work in other parts of the United States. From 1940 to 1960, the index of man-hours of farm work dropped from 191 to 92 for the United States as a whole and in the Delta States of Alabama, Louisiana, and Mississippi from 247 to 93.