This sample includes counties from Michigan, Indiana, Ohio and Wisconsin. Of these states, only Ohio did not have right-to-work legislation passed by 2018, the year from which our employment data is collected. Manufacturing accounts for roughly 23% of total private employment in this sample. While not statistically significant (p-value of 0.118) due to a large standard error, the direct effect of right-to-work on a given county in this sample is to increase manufacturing employment as a percentage of total private employment by 5.99 percentage points, or roughly 26%. The collective spillover effect on other counties is to reduce manufacturing employment share by 30%, a result that is statistically significant. These two effects largely cancel each other out, leaving manufacturing employment as a share of private employment statistically unchanged across the entire four state region. However, these results do tend to support a realignment of manufacturing employment opportunities toward right-to-work counties.
The same qualitative pattern is observed in both the construction and the transportation and warehousing industries. That is, the direct effect of right-to-work is to increase these industries employment share in right-to-work counties, while the indirect effect is to reduce employment share collectively across non-right-to-work counties. In the case of the construction industry, the effects cancel each other out such that there is a near zero total effect across the region. In transportation and warehousing, the total effect is statistically insignificant due to a large standard error; however, it is relatively large in magnitude and negative, suggesting that total industry employment in the four-state region is lower by potentially 26%.