One hundred years ago this month, an unforeseen army of young women, most of them immigrants, shook New York City’s garment industry to its core. In the late summer of 1909, workers at three of the city’s large shirtwaist manufacturing companies lost patience with the dangerous and unfair working conditions in their garment shops and walked off the job. In late November, with those strikes flagging, Local 25 of the International Ladies Garment Workers Union (ILGWU) called for a general strike in the shirtwaist industry. And strike more than 20,000 waistmakers did, enduring hardship, derision, beatings, and even jail for 11 long weeks. ASHP’s Heaven Will Protect the Working Girl documentary tells the story of this remarkable labor uprising, and the social world that gave rise to it.

The strikers squared off not only against their employers who were doing their best to get scab workers on the job but also against police and judges who took a dim view of their right to walk the picket lines. One journalist described the beating that union activist Clara Lemlich received at the hands of enforcers hired by company owners:

The girls, headed by teen-age Clara Lemlich, described by union organizers as a pint of trouble for the bosses, began singing Italian and Russian working-class songs as they paced in twos before the factory door. Of a sudden, around the corner came a dozen tough-looking customers, for whom the union label gorilla seemed well-chosen.

Stand fast, girls, called Clara, and then the thugs rushed the line, knocking Clara to her knees, striking at the pickets, opening the way for a group of frightened scabs to slip through the broken line. Fancy ladies from the Allen Street red-light district climbed out of cabs to cheer on the gorillas. There was a confused melee of scratching, screaming girls and fist-swinging men and then a patrol wagon arrived. The thugs ran off as the cops pushed Clara and two other badly beaten girls into the wagon.

Bolstering their own considerable determination, the strikers found powerful allies in members of the Women’s Trade Union League, a cross-class coalition of women reformers whose elite members provided financial support, publicity, and picket-line solidarity to their working-class sisters. But solidarity had its limits, as the African-American newspaper the New York Age explained in January 1910:

We too have been importuned by a lady of wealth and social position to come to the assistance of the striking girl waistmakers. We have also had the case of the shirtwaist manufacturers presented to us, and through our advertisement columns colored girls have found employment as ironers with the firms whose employees are now on strike. . . .

Prior to the strike of the waistmakers, Negro girls were not asked to join the union. They not being asked amounted practically to an exclusion from the union and the workshop. . . . More than that, we asked the philanthropic sponsor for the striking girls would the union admit Negro girls in the future without discrimination as to employment should they refrain from taking the positions now open. As yet we have received no such assurance. Could we therefore, in sense and justice, advise competent Negro girls, while idle and until now denied employment, to turn down this opportunity? Why should Negro working girls pull white working girls chestnuts out of the fire?

. . . The Negro will continue to be the pivot upon which future strikes will turn so long as labor will ignore his right to work and thwart his ambition to work in the mechanical world. The friends and leaders of labor should consider the Negro in days of prosperity as well as in those of adversity.

By February 15, 1910, when the ILGWU called off the strike, 96% of the city’s shirtwaist firms had signed contracts granting most of the strikers demands: a 52 hour work week, four holidays with pay per year, an equitable division of work during slack seasons, no more charging workers for needles and other supplies, and no discrimination against union activists. If the workers did not succeed at guaranteeing union representation to all workers, their uprising set off strikes by garment workers in other cities and mortally wounded male union leaders’ notion that women workers were not worth organizing. Between 1909 and 1913 nearly 400,000 clothing workers in the U.S. became union members.

Today, nearly half of all union members in the U.S. are women, yet they remain underrepresented in union leadership.