According to the U.S. Department of Labor, the number of union members in Wisconsin has dropped 40% since 2011's controversial law that took away collective bargaining rights from public-sector unions. Public-sector unions are now only allowed to bargain over base wage increases that are less than or equal to inflation. The policy has resulted in membership falling drastically in the state's public school teachers union. Union numbers fell even more after the state's right to work legislation passed in 2015. Union membership on a national level has also fallen, primarily because of the replacement of manufacturing jobs by technology.
See "Union membership in Wisconsin down nearly 40 percent since 2011 law that sparked protests", Chicago Tribune, January 30, 2017