These men and women are Chicago Stockyards employees, once the largest meat butchering and processing facility in the world.
Since the 1870s, these workers had tried to organize unions to improve their conditions. With the passage of the National Labor Relations Act in 1935, the stockyard workers finally had a legal right to form a union, which they began doing at different packinghouses after the law's passage.
Companies often divided workers by race and gender, so that groups did not see a united interest. The United Packinghouse Workers, a CIO (Congress of Industrial Organizations) union, brought all workers -- male and female, African-American, white and Hispanic, together into one union to fight for their common well being. This 1941 photo is from a UPW rally.