By the mid-1930s many of Chicago's manufacturing workers were involved in building a new institution of their own, a network of national-level industrial unions designed to make demands of the employers they held responsible for much of their suffering. Drastic hour and wage cuts, total disregard for seniority in layoffs and rehiring, deterioration of benefits, and rejection of any real collective bargaining despite the federal government's pledge under the National Industrial Recovery Act and later the Wagner Act to protect it – these and other abuses drove Chicago's factory workers to take action. Thousands of steelworkers, meatpackers, and makers of agricultural machinery bravely put their signatures on union cards, smuggled union material into their plants, met secretly to strategize, and orchestrated work stoppages and strikes when necessary to force their bosses to bargain collectively for better working conditions. Workers acted despite fear of reprisals from employers whose power over them had grown as the depression shut off the “safety valve” of quitting utilized in the 1920s.

By 1940, one in three workers in Chicago manufacturing had become a union member. In plant after plant, workers won contracts from their employers, or at least demonstrated their support for the new unions affiliated with the national Congress (initially Committee) of Industrial Organizations (CIO).