Why Did Trump Carry the Rustbelt? One Reason: Union Membership Had Dropped

In Defying the Odds, we suggest an under-examined reason why Democrats were unexpectedly weak in key industrial states;  union membership was way down.

At the high point of their influence many years ago, they [labor unions] supplied the people who worked the phones, stuffed the envelopes and walked the precincts on behalf of the Democrats.  In some states, they still were a significant force, but overall, they were on the wane. Between 1983 and 2015, union membership as a share of employed workers plunged by almost half, from 20.1 percent to 11.1 percent.   Not coincidentally, the drop-off was steepest in five industrial states that voted Republican in the 2016 presidential race 

 Percentage Change in Union Density, Selected States, 1983-2015

                                    1983                2015                Change

Wisconsin                    24.2                 08.4                -15.8

Michigan                     30.8                 15.3                 -15.5

Indiana                        25.2                 10.1                 -15.1

Pennsylvania               27.7                 13.4                 -14.3

Ohio                             25.3                 12.4                 -12.9

Source: Barry T. Hirsch and David A. Macpherson, “State Union Membership Density 1964-2015,” http://unionstats.gsu.edu/State_Union_Membership_Density_1964-2015.xlsx; Barry T. Hirsch, David A. Macpherson, and Wayne G. Vroman, “Estimates of Union Density by State,” Monthly Labor Review 124, No. 7, July 2001, http://unionstats.gsu.edu/MLR_7-01_StateUnionDensity.pdf