This iconic photo is often seen in internet articles about labor struggles. It's almost always used without saying what it's about.
The women are shirtwaist makers and members of the International Ladies Garment Workers Union. Shirtwaist is an early term for blouse. The women are part of what was called The Uprising of the 20,000, a strike by 20,000 workers in New York City's garment district in 1909. They were primarily young, single, Jewish, immigrant and female workers who worked long days for $6 for a week under various kinds of harsh and humiliating conditions.
Often the picture is used in articles about the Triangle Shirtwaist Factory Fire. The Triangle Shirtwaist Factory's owners were not among those who signed the labor agreement that brought the Uprising of the 20,000 to an end. When two years later, in 1911, the factory caught fire, many women were trapped inside, as most of the exits were locked to prevent the women from taking breaks. Many jumped to their deaths from upper floors, and in all 146 women died.
A photo you don't often see reproduced is that of Clara Lemlich, above, who organized the Uprising of the 20,000. A Jew who had immigrated to New York with her family from the Ukraine, Lemlich was a prolific organizer. When she stopped working to raise her children she organized housewives, who staged some of the first rent strikes, and whose boycotts and rolling pickets of New York City butchers made them stop overcharging for meat in working class immigrant and African American neighborhoods.
Lemlich never stopped organizing, even organizing the workers in the rest home where she died. It could be that Clara Lemlich is never mentioned in most Labor histories because she was a woman, a strong and successful one, and a Communist.
(Note: The first photo is in a Library of Congress' collection of glass negative photos attributed to the Bain News Service, which was begun by photographer George Bain. There's no individual credit given for most of the photos, which are available widely on the internet including at the Library of Congress or at a Flickr site where they are more easily viewed. Among the photos, I recognized many of baseball players of the time I've seen here and there. It's quite a diverse collection, though, including many photos of old ships, battleships, dirigibles, celebrities and rich people.
The photo of Clara Lemlich wearing a shirtwaist is from the archives of the International Ladies Garment Workers Union (of which she was an officer) at Cornell University. Lemlich is interesting also for the fact that was a forerunner of a type of feminist who don't downplay the fact that women are women. While doctrinaire male and female counterparts in the Labor Movement and Communist Party hierarchy criticized female workers for reading cheap romance novels and wearing high heels, Lemlich defended them, foreseeing the problem of class division in feminism for which it is often criticized today.