Declines in union density explain a considerable portion of rising US inequality among unionized and non-unionized workers. However, how union density regulates non-union wages is mainly speculative. I test the moral economy hypothesis that union density reduces inequality, in part, by fostering egalitarian wage norms that regulate compensation practices and redistributive policies. Variance function regressions suggest that wage norms may explain 12% of union density decline effects on rising within-group wage inequality between 1983 and 2018. Findings provide support for the moral economy perspective and an empirical foundation for the causal relationship between unions and inequality.

工会密度的下降在很大程度上解释了美国工会和非工会工人之间不平等现象的加剧。然而，工会密度如何调节非工会工资主要是推测性的。我检验了道德经济假设，即工会密度可以部分通过促进规范薪酬实践和再分配政策的平等工资规范来减少不平等。方差函数回归表明，工资标准可以解释 1983 年至 2018 年间工会密度下降 12% 对群体内工资不平等加剧的影响。研究结果为道德经济观点提供了支持，并为工会与不平等之间的因果关系提供了实证基础。