Interstate Variations in Private Sector Union Density in the U.S.

This paper uses union density variations across state and state-industry cells in 1985, 1995, and 2005 to examine the factors that contributed to the decline in private sector unionization in the U.S. In addition to the conventional variables, it develops two measures to gauge the effects of union-management strife. Estimations indicate that union density varied directly with union organizing efforts and inversely with the employer opposition to unionization. Decomposition analysis reveals, however, that these variables do not explain why union density declined because changes in their marginal effects were favorable to unionization. Declining union density instead is attributable mostly to the shift factors subsumed under the intercept term over 1985–1995, and shift factors cum negative changes in sensitivity of unionization to workforce characteristics over 1995–2005.