Abstract: The role of twentieth-century agricultural mechanization in changing the productivity, employment opportunities, and appearance of rural America has long been appreciated. Less attention has been paid to the impact made by farm tractors, combines, and associated equipment on the standard of living of the U.S. population as a whole. This paper demonstrates, through use of a detailed counterfactual analysis, that mechanization in the production of farm products increased GDP by more than 8.0 percent, using 1954 as a base year. This result suggests that studying individual innovations can significantly increase our understanding of the nature of economic growth.