The Wagner Act, passed by a Democratic-controlled Congress in 1935, provided unprecedented federal protections for American labor unions. The Taft-Hartley Act, passed by a Republican-controlled Congress just twelve years later, effectively rolled back significant parts of Wagner. Previous research on Taft-Hartley identifies three factors that led to this anti-labor backlash. First, the American public was repulsed by the large strike wave that followed the end of World War II. Second, southern Democrats were concerned that powerful labor unions would organize African Americans and upset the South's racial hierarchy. Third, the Republican Party was increasingly embracing a conservative, probusiness ideology. This article contributes a new angle to this old debate by exploring the role of the CIO, its 1943 decision to create the country's first political action committee (PAC), and the consequences of its informal alliance with the Democratic Party. Using original data on CIO density and congressional voting on the Taft-Hartley Act, we demonstrate that CIO strength polarized the parties: higher levels of CIO density led Democrats to vote in favor of organized labor but led Republicans to vote in an increasingly anti-labor manner.
