Monopsony in the US Labor Market

This paper quantifies employer market power in US manufacturing and how it has changed over time. Using administrative data, we estimate plant-level markdowns-the ratio between a plant's marginal revenue product of labor and its wage. We find most manufacturing plants operate in a monopsonistic environment, with an average markdown of 1.53, implying a worker earning only 65 cents on the marginal dollar generated. To investigate long-term trends for the entire sector, we propose a novel, theoretically grounded measure for the aggregate markdown. We find that it decreased between the late 1970s and the early 2000s, but has been sharply increasing since.