
by Kyung Joon Han and Eric Graig Castater
There has been a longstanding consensus in the labor politics literature that countries and time periods with higher union density (the proportion of workers that belong to a union), union coverage (the proportion of workers covered by a union bargained contract, regardless of whether they are union members), and/or wage bargaining level (the level at which unions and employers bargain over wages, ranging from the firm to the national level, with the latter signifying a “higher” level of wage bargaining) are associated with lower levels of wage inequality.
Indeed, much of this scholarship has found that such “union presence” variables help explain a substantial portion of the cross-national and over-time variation in wage inequality in the wealthy democracies. However, recent evidence indicates that such a union effect on wage inequality disappeared during the 1990s due to the decentralization of bargaining structure as well as the decline of union density and union coverage.
In short, unions are only able to reduce wage inequality when they have substantial organizational strength.
In an article recently published in Research in Social Stratification and Mobility, we examine whether unions still have an effect on wage inequality, but do so by focusing on what we term the capital and skill mechanisms, the primary means by which unions reduce wage inequality.








