The paper by Claudia Goldin and Lawrence F. Katz explores the origins of technology-skill complementarity in manufacturing from 1909 to 1929. They argue that the adoption of continuous-process and batch production methods, along with the switch to purchased electricity, led to an increase in the relative demand for skilled labor. The authors use historical data from U.S. censuses and manufacturing surveys to analyze the relationship between capital intensity, electricity use, and the education level of workers. They find that industries with higher capital intensity and greater use of purchased electricity employed more highly educated blue-collar workers and paid them significantly higher wages. The study also links these findings to the high-school movement (1910-1940), suggesting that the rapid increase in skilled labor may have prevented rising inequality with technological change. The authors conclude that capital-skill and technology-skill complementarity emerged as particular technologies spread, reinforcing the trend through automation and increased demand for skilled workers.The paper by Claudia Goldin and Lawrence F. Katz explores the origins of technology-skill complementarity in manufacturing from 1909 to 1929. They argue that the adoption of continuous-process and batch production methods, along with the switch to purchased electricity, led to an increase in the relative demand for skilled labor. The authors use historical data from U.S. censuses and manufacturing surveys to analyze the relationship between capital intensity, electricity use, and the education level of workers. They find that industries with higher capital intensity and greater use of purchased electricity employed more highly educated blue-collar workers and paid them significantly higher wages. The study also links these findings to the high-school movement (1910-1940), suggesting that the rapid increase in skilled labor may have prevented rising inequality with technological change. The authors conclude that capital-skill and technology-skill complementarity emerged as particular technologies spread, reinforcing the trend through automation and increased demand for skilled workers.