The Wisconsin State Federation of Labor (WSFL), affiliated with the American Federation of Labor, was the largest federation of labor unions in Wisconsin, from its formation in 1893 at the behest of the to its 1958 merger with the smaller CIO-affiliated to form the . A number of WSFL leaders were also elected to public office in Wisconsin, in part due to its roots in and alliance with the Socialist Party, especially Milwaukee's so-called Sewer Socialists.