The effect of type of union on member-nonmember wage differentials

The union-nonunion wage differential can be decomposed into bargaining and membership effects. While some analysts suggest that they are not separable and that bargaining power is a function of membership density, others argue that they are separable and that the former derives from monopoly power while the latter stems from socialization. Our results support the latter view. We derive estimates of bargaining and membership effects for workers covered by national, industrial, and craft union contracts as well as for all covered workers taken together. Since industrial and craft unions differ in structure and organization, we expect differences in the socialization effects among types of unions. It is clear from our results that union membership per se in each case gives a large positive wage advantage.