Working as an investigative photographer for the National Child Labor Committee, Lewis Hine believed that images of child labor would force citizens to demand change.

The muckraker conned his way into mills and factories from Massachusetts to South Carolina by posing as a Bible seller, insurance agent, or industrial photographer in order to tell the plight of nearly 2 million children.

Carting around a large-format camera and jotting down information in a hidden notebook, Hine recorded children laboring in meatpacking houses, coal mines, and canneries, and in November 1908 he came upon Sadie Pfeifer, who embodied the world he exposed.

A 48-inch-tall wisp of a girl, she was “one of the many small children at work” manning a gargantuan cotton-­spinning machine in ­Lancaster, S.C. Since Hine often had to lie to get his shots, he made “double-sure that my photo data was 100% pure—no retouching or fakery of any kind.”

His images of children as young as 8 dwarfed by the cogs of a cold, mechanized universe squarely set the horrors of child labor before the public, leading to regulatory legislation and cutting the number of child laborers nearly in half from 1910 to 1920.