Union Rents and Market Structure Revisited

Several recent studies give conflicting evidence on whether market power associated with industry concentration is an important source of union rents. Using a 1977 sample of 327 four-digit manufacturing industries, we re-examine the issue with a regression analysis that allows for differential union effects on price-cost margins across three levels of concentration. Large and small firm as well as industry average price-cost margins are analyzed. The results reaffirm those of Hirsch and Connolly (1987), who conclude that the effect of unions on profits is independent of market structure, and thus market power is not an important source of union rents. We find that unionization: (1) reduces industry profits in all three concentration groups with statistically insignificant differential effects, and (2) has a greater negative effect on the profits of large firms than it does on the profits of small firms, regardless of the concentration category